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# International Journal of Heat and Mass Transfer (v.52, #3-4)

On the scale effect and scale-up in the column apparatuses 1. Influence of the velocity distribution by K. Panayotova; M. Doichinova; Chr. Boyadjiev (

*pp. 543-547*).

**Keywords:** Column apparatuses; Mass transfer; Velocity distribution; Scale-up

About use of a method of direct numerical solution for simulation of bulk condensation of supersaturated vapor by N.M. Kortsensteyn; E.V. Samuilov; A.K. Yastrebov (

*pp. 548-556*).

**Keywords:** Nucleation; Bulk condensation; Distribution function; Kinetic equation; Numerical solution

Heat transfer in all pipe flow regimes: laminar, transitional/intermittent, and turbulent by J.P. Abraham; E.M. Sparrow; J.C.K. Tong (

*pp. 557-563*).

*Re*=2300 and 10,000. It was found that over the range

*Re*>4800, both the present predictions and those of the Gnielinski formula [V. Gnielinski, New equations for heat and mass transfer in turbulent pipe and channel flow, Int. Chem. Eng. 16 (1976) 359–367] are very well supported by the experimental data. However, the Gnielinski model is less successful in the range from 2300 to 3100. In that range, the present predictions and those of Churchill [S. Churchill, Comprehensive correlating equations for heat, mass, and momentum transfer in fully developed flow in smooth tubes, Ind. Eng. Chem. Fundam. 16 (1977) 109–116] are mutually reinforcing. Heat transfer results in the development region have also been obtained. Typically, regardless of the Reynolds number, the region immediately downstream of the inlet is characterized by laminar heat transfer. After the breakdown of laminar flow, a region characterized by intermittent heat transfer occurs. Subsequently, the flow may become turbulent and fully developed or the intermittent state may persist as a fully developed regime. The investigation covered both of the basic thermal boundary conditions of uniform heat flux (UHF) and uniform wall temperature (UWT). In the development region, the difference between the respective heat transfer coefficients for the two cases was approximately 25% (UHF>UWT). For the fully developed case, the respective heat transfer coefficients are essentially equal in the turbulent regime but differ by about 25% in the intermittent regime. The reported results are for a turbulence intensity of 5% and flat velocity and temperature profiles at the inlet.

Gold nanoshell density variation with laser power for induced hyperthermia by Jerry Vera; Yildiz Bayazitoglu (

*pp. 564-573*).

_{1}approximation is used to simulate the penetration of laser radiation and subsequent heating of 1-cm slabs of nanoshell-embedded tissue exposed to a 633-nm collimated light source. It is shown that adding too many nanoshells or increasing power can cause overheating in the entry region while leaving the rear region heated only by conduction, producing an undesirable temperature differential. An opposing dual-laser approach is presented that mitigates this issue.

**Keywords:** Photothermal therapy; Hyperthermia; Lasers; Nanoshell; Cancer therapy; Tissue optics

Biofilm affected characteristics of porous structures by Maryam Shafahi; Kambiz Vafai (

*pp. 574-581*).

*Pseudomonas aeruginosa*, are compared with available experimental data. The potential reasons attributing to the differences between the numerical and experimental data are discussed.

**Keywords:** Biofilm; Porous media; Permeability; Porosity

Approximate model for break-up of solidifying melt particles due to thermal stresses in surface crust layer by Leonid A. Dombrovsky (

*pp. 582-587*).

**Keywords:** Melt droplet; Solidification; Corium; Thermal stresses; Breakage; Fuel–coolant interaction

Laminar and turbulent free convection in a composite enclosure by Edimilson J. Braga; Marcelo J.S. de Lemos (

*pp. 588-596*).

*Ra*greater than 10

^{6}. Nusselt number values show that for the range of

*Ra*analyzed there is no significant variation between the laminar and turbulent model solution. When comparing the effects of

*Ra*,

*k*

_{s}/

*k*

_{f}and

*Da*on

*Nu*, results indicate that the solid phase properties have a greater influence in enhancing the overall heat transferred trough the cavity.

**Keywords:** Porous media; Heat transfer; Natural convection; Turbulence modeling

Numerical simulation of parabolic trough solar collector: Improvement using counter flow concentric circular heat exchangers by O. García-Valladares; N. Velázquez (

*pp. 597-609*).

**Keywords:** Concentration; PTC; Numerical model; Solar energy; Heat exchanger; Double pipe

CHF determination for high-heat flux phase change cooling system incorporating both micro-channel flow and jet impingement by Myung Ki Sung; Issam Mudawar (

*pp. 610-619*).

^{2}, which is the highest value ever achieved for a dielectric coolant at near atmospheric pressure. It is shown the hybrid cooling configuration involves complex interactions between circular jets and micro-channel flow, and unusual spatial variations of void fraction and liquid velocity. These variations are ascertained using the Developing Homogeneous Layer Model (DHLM) in which the micro-channel flow is described as consisting of a homogeneous two-phase layer along the heated wall and a bulk liquid layer. CHF is determined by a superpositioning technique that consists of dividing the heated wall into two portions, one dominated by jet impingement and the other micro-channel flow. This technique is shown to be highly effective at predicting the CHF data for the hybrid cooling configuration.

Transition to a periodic flow induced by a thin fin on the sidewall of a differentially heated cavity by Feng Xu; John C. Patterson; Chengwang Lei (

*pp. 620-628*).

**Keywords:** Fin; Differentially heated cavity; Oscillations; Heat transfer

Multi-artery, heat-pipe spreader by D.H. Min; G.S. Hwang; M. Kaviany (

*pp. 629-635*).

**Keywords:** Multiple liquid artery; Vapor chamber; Heat pipe; Optimal design; Dry out; Wick superheat

Study on flow and heat transfer characteristics of heat pipe with axial “

*Ω*”-shaped microgrooves by Yongping Chen; Chengbin Zhang; Mingheng Shi; Jiafeng Wu; G.P. Peterson (

*pp. 636-643*).

*Ω*”-shaped grooves has been conducted to study the maximum heat transport capability of these types of heat pipes. The influence of variations in the capillary radius, liquid–vapor interfacial shear stress and the contact angle are all considered and analyzed. The effect of vapor core and wick structure on the fluid flow characteristics and the effect of the heat load on the capillary radius at the evaporator end cap, as well as the effect of the wick structure on the heat transfer performance are all analyzed numerically and discussed. The axial distribution of the capillary radius, fluid pressure and mean velocity are obtained. In addition, the calculated maximum heat transport capability of the heat pipe at different working temperatures is compared with that obtained from a traditional capillary pressure balance model, in which the interfacial shear stress is neglected. The accuracy of the present model is verified by experimental data obtained in this paper.

**Keywords:** Heat pipe; Microgrooves; Capillary radius; Maximum heat transport capability

Incorporating boundary conditions in the heat conduction model by V. Bertola; E. Cafaro (

*pp. 644-646*).

Pulsating flow and convective heat transfer in a cavity with inlet and outlet sections by A. Velazquez; J.R. Arias; J.L. Montanes (

*pp. 647-654*).

**Keywords:** Cavity; Unsteady flow; Convective heat transfer

Low Reynolds number scalar transport enhancement in viscous and non-Newtonian fluids by D.R. Lester; M. Rudman; G. Metcalfe (

*pp. 655-664*).

*Pe*=10

^{3}, which furthermore increases with

*Pe*.

**Keywords:** Heat and mass transfer; Chaotic advection; Parametric variation; Numerical methods

Thermal conductivity of a clay-based aerogel by S.R. Hostler; A.R. Abramson; M.D. Gawryla; S.A. Bandi; D.A. Schiraldi (

*pp. 665-669*).

**Keywords:** Aerogel; Clay; Thermal conductivity; Effective medium

Dynamics and temperature of droplets impacting onto a heated wall by G. Castanet; T. Liénart; F. Lemoine (

*pp. 670-679*).

**Keywords:** Drop impact; Laser-induced fluorescence; Temperature measurement; Spray cooling

Simulation of turbulent impinging jet into a cylindrical chamber with and without a porous layer at the bottom by Daniel R. Graminho; Marcelo J.S. de Lemos (

*pp. 680-693*).

*k*–

*ε*model, which uses the same set of equations for both the fluid layer and the porous matrix. The numerical technique employed is the control volume method in conjunction with a boundary-fitted coordinate system. One unique computational grid is used to compute the entire heterogeneous medium. The SIMPLE algorithm is applied to relax the system of algebraic equations. Results indicate that the permeability of the porous layer and the height of the fluid layer significantly affect the flow pattern. The effect of the porous layer thickness was less pronounced in affecting the flow behavior in the fluid layer.

**Keywords:** Turbulent flow; Porous media; Numerical methods; Impinging jet; Modeling

Numerical solution for the linear transient heat conduction equation using an Explicit Green’s Approach by W.J. Mansur; C.A.B. Vasconcellos; N.J.M. Zambrozuski; O.C. Rotunno Filho (

*pp. 694-701*).

**Keywords:** Linear transient heat conduction; Numerical Green’s matrix; ExGA; Time integration

Approximate solutions of lean premixed combustion in porous media with reciprocating flow by Jun-Rui Shi; Mao-Zhao Xie; Gang Li; Hong Liu; Ji-Tang Liu; Hong-Tao Li (

*pp. 702-708*).

**Keywords:** Premixed combustion; Reciprocating flow; Flammability limit; Approximate solution

Stability of conducting viscous film flowing down an inclined plane with linear temperature variation in the presence of a uniform normal electric field by Asim Mukhopadhyay; Anandamoy Mukhopadhyay (

*pp. 709-715*).

**Keywords:** Thin film; Finite amplitude stability analysis; Electrodynamic instability; Marangoni instability

Theoretical model for fast bubble growth in small channels with reference to startup of capillary pumped loops used in spacecraft thermal management systems by Tim J. LaClair; Issam Mudawar (

*pp. 716-723*).

Numerical prediction of natural convection in vented cavities using restricted domain approach by S. Anil Lal; C. Reji (

*pp. 724-734*).

*T*

_{w}), is the heat source for the cavity and the side walls are adiabatic. A restricted domain approach that predicts the regions of inflow, outflow and velocity distributions is employed. The applicability of two types of pressure boundary conditions at entry and exit regions are studied and compared. Non-linear coupled partial differential equations governing natural convection are solved on a structured non-uniform staggered grid using a second-order accurate upwind least square scheme for discretising the convection terms, central difference scheme for diffusion terms and SIMPLER algorithm for pressure–velocity decoupling. An in-house code is developed and is validated with the results of three classical natural convection problems. Simulations have been carried out for a wide range of thermal parameter, Rayleigh numbers (10

^{4}⩽

*Ra*⩽10

^{8}), orientation of the cavity about horizontal (0⩽

*δ*⩽180) and geometrical parameter, vent ratio(0.05⩽DL⩽0.25). The numerical simulation predicts the dimensionless mass flow rate through the cavity and variation of local Nusselt number over the hot wall. A correlation for average Nusselt number is developed in terms of Rayleigh number and angle of tilt of the cavity forDL⩾0.1.

**Keywords:** Natural convection; Vented cavities; Restricted domain approach; SIMPLER algorithm; Upwind least square scheme

Transport properties of liquid argon in krypton nanochannels: Anisotropy and non-homogeneity introduced by the solid walls by F. Sofos; T. Karakasidis; A. Liakopoulos (

*pp. 735-743*).

*σ*, below which the behavior of transport properties is affected in comparison to bulk properties. In fact for small width values, diffusion coefficient is highly anisotropic, the component normal to the wall being the smaller one. For the same width range, diffusivities along all directions are higher in the central layers than those close to the walls. Similarly, shear viscosity increases for small channel width values while thermal conductivity decreases. All properties approach bulk values as the channel width increases. The layers close to the walls always present distinctly different behavior due to the interaction with the wall atoms. The observed behavior is of particular importance in the design of nanofluidic devices.

**Keywords:** NEMD simulation; Nanofluid dynamics; Nanoscale phenomena; Transport properties; Non-continuum effects

Boiling behaviors and critical heat flux on a horizontal plate in saturated pool boiling of water at high pressures by Hiroto Sakashita; Ayako Ono (

*pp. 744-750*).

**Keywords:** Pool boiling; Critical heat flux; High pressure; Macrolayer; Observation; Primary bubble; Coalesced bubble

Coupled heat and mass transfer through asymmetric porous membranes with finger-like macrovoids structure by Li-Zhi Zhang (

*pp. 751-759*).

**Keywords:** Heat transfer; Mass transfer; Asymmetric membranes; Finger-like macrovoids

Modeling of the heat transfer and flow features of the thermal plasma reactor with counter-flow gas injection by Gui-Qing Wu; He-Ping Li; Cheng-Yu Bao; Xi Chen (

*pp. 760-766*).

**Keywords:** Thermal plasma; Reactor; Modeling; Counter-flow injection; Swirling effect

Bubble growth with chemical reactions in microchannels by B.R. Fu; Chin Pan (

*pp. 767-776*).

_{2}bubbles due to chemical reactions of sulfuric acid and sodium bicarbonate in three types of microchannels: one with uniform cross-section, one converging, and another one diverging. The Y-shaped test section, composed of main and two front microchannels, was made of P-type 〈100〉 orientation SOI (silicon on insulator) wafer. Bubble nucleation and growth in microchannels under various conditions were observed using a high-speed digital camera. The theoretical model for bubble dynamics with a chemical reaction is reviewed or developed. In the present study, no bubble was nucleated at the given inlet concentration and in the range of flow rate in the converging microchannel while the nucleation and growth of bubbles were observed in the diverging and uniform cross-section microchannels. Bubbles are nucleated at the channel wall and the equivalent bubble radius increases linearly during the initial period of the bubble growth. The bubble growth behavior for a particular case, without relative motion between the bubble and liquid, shows that the mass diffusion controls the bubble growth; consequently, the bubble radius grows as a square root of the time and agrees very well with the model in the literature. On the other hand, for other cases the bubbles stay almost at the nucleation site while growing with a constant gas product generation rate resulting in the instant bubble radius following the one-third power of the time.

**Keywords:** Bubble growth; Microchannel; Two-phase flow; Chemical reaction

Heat transfer in particulate flows with Direct Numerical Simulation (DNS) by Zhi-Gang Feng; Efstathios E. Michaelides (

*pp. 777-786*).

**Keywords:** Particulate flow; Solid and fluid interaction; Heat transfer; Immersed boundary method

Experimental and numerical studies of AISI1020 steel in grind-hardening by Jianhua Zhang; Peiqi Ge; Tien-Chien Jen; Lei Zhang (

*pp. 787-795*).

**Keywords:** Grind-hardening; Numerical study; Surface hardening; Grinding temperature field

Assessment of structure effects on the thermal conductivity of two-phase porous geomaterials by Jean Côté; Jean-Marie Konrad (

*pp. 796-804*).

**Keywords:** Thermal conductivity; Solid; Fluid; Porosity; Particles shape; Cement

Study on condensation heat transfer characteristics of wet paper in steam heating process by Tsutomu Kawamizu; Takeshi Kaneko; Setsuo Suzuki; Takaharu Tsuruta (

*pp. 805-813*).

**Keywords:** Porous media; Permeability; Suction pressure; Condensation; Heat transfer; Mass transfer

Measurement of surface dryout near heating surface at high heat fluxes in subcooled pool boiling by Ayako Ono; Hiroto Sakashita (

*pp. 814-821*).

**Keywords:** Pool boiling; Critical heat flux; Macrolayer; Dryout; Subcooled boiling; Conductance probe

Numerical studies on laminar natural convection inside inclined cylinders of unity aspect ratio by Vinoj Kurian; Mahesh N. Varma; A. Kannan (

*pp. 822-838*).

^{3}to 3.1×10

^{4}by changing the specified end wall temperatures. The critical Rayleigh number was estimated to be 3800 for the vertical cylinder. Relaxing the convergence criterion caused false hysteresis in the converged results for the vertical cylinder. Typical natural convective fluid flow and temperature patterns obtained under laminar flow conditions are illustrated for various inclinations ranging from 0° to 180°. Flow visualization studies revealed complex three-dimensional patterns. Different thermal–hydrodynamic regimes were identified and were classified in terms of Rayleigh number and angle of inclination. Empirical correlations for the Nusselt number and maximum velocities in the domain as a function of the inclination angle and Rayleigh number are developed.

**Keywords:** Natural convection; Cylinder inclination; Flow patterns; Maximum convective velocity; Nusselt number; Critical Rayleigh number

Effects of Reynolds and Prandtl numbers on heat transfer from a square cylinder in the unsteady flow regime by Akhilesh K. Sahu; R.P. Chhabra; V. Eswaran (

*pp. 839-850*).

*Re*⩽160 and 0.7⩽

*Pr*⩽50 (the maximum value of Peclet number being 4000). A semi-explicit finite volume method has been used on a non-uniform collocated grid arrangement to solve the governing equations. Using the present numerical results, simple heat transfer correlations are obtained for the constant temperature and constant heat flux conditions on the solid square cylinder. In addition, the variation of the time averaged local Nusselt number on the each face of the obstacle and representative isotherm plots are presented to elucidate the role of Prandtl number on heat transfer in the unsteady flow regime.

**Keywords:** Square cylinder; Unsteady flow; Prandtl number; Nusselt number; Strouhal number

Numerical heat transfer analysis of encapsulated ice thermal energy storage system with variable heat transfer coefficient in downstream by Aytunc Erek; Ibrahim Dincer (

*pp. 851-859*).

**Keywords:** Heat transfer; Phase change; Solidification; Phase change; Encapsulated ice; Energy storage

Modeling heat transfer in Bi

_{2}Te

_{3}–Sb

_{2}Te

_{3}nanostructures by Arvind Pattamatta; Cyrus K. Madnia (

*pp. 860-869*).

_{2}Te

_{3}–Sb

_{2}Te

_{3}nanostructures are gaining importance for use in thermoelectric applications following the finding that the Bi

_{2}Te

_{3}–Sb

_{2}Te

_{3}superlattice exhibits a figure of merit, ZT=2.4, which is higher than conventional thermoelectric materials. In this paper, thermal transport in the cross-plane direction for Bi

_{2}Te

_{3}–Sb

_{2}Te

_{3}nanostructures is simulated using the Boltzmann transport equation (BTE) for phonon intensity. The phonon group velocity, specific heat, and relaxation time are calculated based on phonon dispersion model. The interfaces are modeled using a combination of diffuse mismatch model (DMM), and the elastic acoustic mismatch model (AMM). The thermal conductivity for the Bi

_{2}Te

_{3}–Sb

_{2}Te

_{3}superlattice is compared with the experimental data, and the best match is obtained for specularity parameter,

*p*, of 0.9. The present model is extended to solve for thermal transport in 2-D nanowire composite in which Sb

_{2}Te

_{3}wires are embedded in a host material of Bi

_{2}Te

_{3}. Unlike in bulk composites, the results show a strong dependence of thermal conductivity, temperature, and heat flux on the wire size, wire atomic percentage, and interface specularity parameter. The thermal conductivity of the nanowire is found to be in the range of 0.034–0.74 depending on the atomic percentage and the value of

*p*.

**Keywords:** Bi; _{2}; Te; _{3}; Sb; _{2}; Te; _{3}; Boltzmann equation; Nanostructures; Superlattice; Nanowire

Critical review of flow boiling heat transfer of CO

_{2}–lubricant mixtures by Xiumin Zhao; Pradeep Bansal (

*pp. 870-879*).

_{2}–lubricant mixtures. Some of the immiscible lubricants in CO

_{2}include alkyl naphthalene/alkylbenzne (AN/AB) and polyalphaolefin (PAO), while polyalkylene glycol (PAG) is partially miscible, and polyol ester (POE) is completely miscible. The effect of oil concentration, vapour quality, heat and mass fluxes and saturation temperature is addressed. One database has been created by collecting the experimental data from the open literature on the flow boiling heat transfer of CO

_{2}–lubricant mixtures, along with empirical correlations. A simple simulation model has been developed in EES software package to compare the empirical correlations with the CO

_{2}–lubricant mixtures experimental database. Most empirical correlations fail to predict the flow boiling heat transfer coefficient in good agreement with the experimental data. Hence, further research is needed to develop appropriate correlations for the flow boiling heat transfer of CO

_{2}–lubricant mixtures.

**Keywords:** Flow boiling heat transfer; CO; _{2}; –lubricant mixture; In-tube flow

Heat transfer in tilted reciprocating anti-gravity open thermosyphon by Tsun Lirng Yang; Shyy Woei Chang (

*pp. 880-893*).

*Nu*) data from two opposite upper and lower edges of a tilted reciprocating anti-gravity open tubular thermosyphon that emulates closely the realistic ‘

*shaker-bored*’ cooling conditions inside a piston of marine propulsive diesel engine. The impacts of thermosyphon inclination on heat transfer are described by way of comparisons between two sets of

*Nu*data generated from the vertical and tilted reciprocating thermosyphons. Nusselt number differences between two opposite upper (

*Nu*

_{Upper}) and lower (

*Nu*

_{Lower}) edges along the tilted thermosyphon are amplified as the reciprocating force increases; while no appreciable differences between

*Nu*

_{Upper}and

*Nu*

_{Lower}are observed in the

*tilted static*thermosyphon or in the

*vertical*static and reciprocating thermosyphon. For such tilted reciprocating open thermosyphon, the individual and interactive influences of inertial, reciprocating and buoyancy forces on heat transfer are described for both sub-cooled (single phase) and superheated (two phase) conditions. Due to the synergistic effects of inertial force, reciprocating force and buoyancy interactions for all the experimental conditions tested, the worst heat transfer scenarios in terms of the axially averaged

*Nu*values in the

*tilted reciprocating open thermosyphon*fall to the level of 0.82 times of the static levels. A set of empirical heat transfer correlations which permits the evaluation of axially averaged Nusselt numbers is developed to assist the design activity of such piston cooling system.

**Keywords:** Open thermosyphon; Reciprocating flow; Piston cooling

Non-uniform double slot suction (injection) into water boundary layer flows over a cylinder by P. Saikrishnan; S. Roy; I. Mohammed Rizwan Sadiq; Bishun D. Pandey (

*pp. 894-898*).

Three dimensional mixed convection in plane symmetric-sudden expansion: Symmetric flow regime by M. Thiruvengadam; B.F. Armaly; J.A. Drallmeier (

*pp. 899-907*).

^{2}. The Reynolds number and the range of wall heat flux are selected to insure that the flow remains laminar and symmetric in this geometry and reverse flow does not develop at the exit section of the duct. Results for the velocity, temperature, and the Nusselt number distributions are presented, and the effects of the buoyancy force and the duct’s aspect ratio on these results are discussed.

**Keywords:** Laminar mixed convection; Internal flow; Separated flow; Heat transfer; 3-D Numerical simulation

Investigation of coated tubes in cross-flow boiling by Vikas J. Lakhera; Akhilesh Gupta; Ravi Kumar (

*pp. 908-920*).

*G*=258.49kg/m

^{2}s), heat flux from 12 to 45kW/m

^{2}, surface roughness (

*Ra*) from 0.3296 to 4.731μm. Nominal enhancement in heat transfer coefficient at higher mass flux may be attributed to the continued nucleation at the uppermost surfaces (in the wake region of the flow) of the rougher tubes thereby increasing the overall heat transfer rate. The flow boiling data was found to best fit the Kutateladze asymptotic equation

*h*=

*h*

_{l}[1+(

*h*

_{npb}/

*h*

_{l})

^{ n}]1/

^{ n}with the value of

*n*=2.258 (which is close to the value of

*n*=2 suggested by Kutateladze).

**Keywords:** Boiling heat transfer; Cross-flow; Surface roughness; Enhancement

Large-eddy simulation of an impinging jet in a cross-flow on a heated wall-mounted cube by D. Rundström; B. Moshfegh (

*pp. 921-931*).

**Keywords:** Large-eddy simulation; Impinging jet in a cross-flow; Reynolds stress model; Electronic cooling

Pulsating convective cooling across two porous-covering heated blocks by Po-Chuan Huang; Yen-Jen Chen; Meir-Chyun Tzou (

*pp. 932-951*).

Capillary-assisted flow and evaporation inside circumferential rectangular micro groove by Z.Z. Xia; G.Z. Yang; R.Z. Wang (

*pp. 952-961*).

**Keywords:** Capillary-assisted evaporation; Micro groove; Rectangular cross section; Extended meniscus

Turbulent flow and heat transfer in discrete double inclined ribs tube by Xiao-wei Li; Ji-an Meng; Zeng-yuan Guo (

*pp. 962-970*).

*k*-

*ε*model in the commercial CFD code, Fluent. The numerical results agree well with the experimental data, with the largest discrepancy of 10% for the Nusselt numbers and 15% for the friction factors. The heat transfer in the DDIR tube is enhanced 100∼120% compared with a plain tube and the pressure drop is increased 170∼250%. The heat transfer rate for the same pumping power is enhanced 30∼50%. Visualization of the flow field shows that in addition to the front and rear vortices around the ribs, main vortices and induced vortices are also generated by the ribs in the DDIR tube. The rear vortex and the main vortex contribute much to the heat transfer enhancement in the DDIR tubes. Optimum DDIR tube parameters are proposed for heat transfer enhancement at the same pumping power.

**Keywords:** Field synergy principle; Heat transfer enhancement; DDIR tube; Longitudinal vortex

Experimental study of multi-hole cooling for integrally-woven, ceramic matrix composite walls for gas turbine applications by Fengquan Zhong; Garry L. Brown (

*pp. 971-985*).

^{5}∼10

^{7}) and a large temperature ratio of the primary flow to the coolant (up to 2.5). Cooling effectiveness determined by the measured surface temperature for the two types of ceramic specimens is investigated. It is found that the multi-hole cooling system for both specimens has a high cooling efficiency and it is higher for the SiC/SiC specimen than for the oxide/oxide specimen. Effects on the cooling effectiveness of parameters including blowing ratio, Reynolds number and temperature ratio, are studied. In addition, profiles of the mean velocity and temperature above the cooling surface are measured to provide further understanding of the cooling process. Duplication of the key parameters for multi-hole cooling, for a representative combustor flow condition (without radiation effects), is achieved with parameter scaling and the results show the high efficiency of multi-hole cooling for the oblique hole, SiC/SiC specimen.

**Keywords:** Integrally-woven ceramic matrix composite; Cooling effectiveness; Reynolds number; Blowing ratio; Temperature ratio

Experimental and theoretical studies of a two-stage pulse tube cryocooler operating down to 3 K by S. Kasthurirengan; G. Srinivasa; G.S. Karthik; D.S. Nadig; U. Behera; K.A. Shafi (

*pp. 986-995*).

_{3}Ni and HoCu

_{2}in layered structures as the first and second stage regenerator materials respectively. With Helium as a working fluid, the pressure oscillations are generated using a 6 kW water-cooled Helium compressor along with an indigenous rotary valve. Different configurations of pulse tube systems have been experimentally studied, by both varying the dimensions of pulse tubes and regenerators as well as the second stage regenerator material composition. The pulse tube Cryocooler has been numerically analyzed by using both the isothermal model and the model based on solving the energy equations. The predicted refrigeration powers as well as the temperature profiles have been compared with the experimental results for specific pulse tube configurations.

**Keywords:** Pulse tube; Cryocooler; Regenerator; Helium; Refrigeration; Numerical modeling

Unsteady heat conduction involving phase changes for an irregular bubble/particle entrapped in a solid during freezing – An extension of the heat-balance integral method by K.R. Lin; P.S. Wei; S.Y. Hsiao (

*pp. 996-1004*).

**Keywords:** Integral method; Heat-balance integral method; Pore formation; Porosity; Bubble capture; Particle inclusion; Contact melting

Transient radiative heating characteristics of slabs in a walking beam type reheating furnace by Sang Heon Han; Seung Wook Baek; Man Young Kim (

*pp. 1005-1011*).

**Keywords:** Reheating furnace; Radiative slab heating; Residence time

Hybrid DNS/LES of high Schmidt number mass transfer across turbulent air–water interface by Yosuke Hasegawa; Nobuhide Kasagi (

*pp. 1012-1022*).

**Keywords:** Turbulence; Air–water interface; Mass transfer; Schmidt number; Surface divergence

Numerical study of mixed convection in a two-dimensional laminar incompressible offset jet flow by K. Kumar Raja; Manab Kumar Das; P. Rajesh Kanna (

*pp. 1023-1035*).

*Pr*=0.71). It is found that the reattachment length is strongly dependent on both

*Re*and

*Gr*for the range considered. Simulations are made to show the effect of entrainment on the recirculation eddy. The variation of the local Nusselt number is presented for various

*Re*and

*Gr*. An empirical correlation of average Nusselt number as a function of Richardson number(Ri=Gr/Re2) and

*Re*has been given.

**Keywords:** Offset jet; Mixed convection; Computation

Laminar natural convection in a square cavity: Low Prandtl numbers and large density differences by T. Pesso; S. Piva (

*pp. 1036-1043*).

*Ra*⩽10

^{8}, in Prandtl number 0.0071⩽

*Pr*⩽7.1 and in Gay-Lussac number 0⩽

*Ga*<2. The effects of the Rayleigh, Prandtl and Gay-Lussac numbers on the Nusselt number are discussed on physical grounds by means of a scale analysis. Finally, based on physical arguments, a heat transfer correlation is proposed, valid for all Prandtl and Gay-Lussac number ranges addressed.

**Keywords:** Natural convection; Heat transfer correlation; Square cavity; Variable properties

Field synergy analysis of laminar forced convection between two parallel penetrable walls by Chenhua Gou; Ruixian Cai; Qibin Liu (

*pp. 1044-1052*).

**Keywords:** Forced convection; Field synergy; Analytical solution

Heat transfer enhancement by flow-induced vibration in heat exchangers by L. Cheng; T. Luan; W. Du; M. Xu (

*pp. 1053-1057*).

**Keywords:** Heat exchanger; Flow-induced vibration; Heat transfer enhancement

Transitional flow patterns behind a backstep with porous-based fluid injection by Go-Long Tsai; Y.C. Lin; W.J. Ma; H.W. Wang; J.T. Yang (

*pp. 1058-1069*).

*Re*

_{h}=2009–3061. By increasing the wall injection velocity ratio gradually, four distinct flow patterns, shifted from pattern A to B, C and D, were categorized. Pressure distributions of these patterns were dominated by the wall injection velocity ratio, and various downstream-flowing tendencies were produced correspondingly. The effect of flow stabilization by decreasing the Reynolds number became more prominent if the wall injection velocity ratio was increased. Due to the existence of a shear layer, a large value of the Reynolds stress was measured near the tip of the step in pattern A. Once the wall injection was initiated, the local strength of Reynolds stress at the same location was decreased. By increasing the wall injection velocity ratio, the region with decreased level of Reynolds stress extended gradually from the tip of backstep to the streamwise location

*x*=0.45

*X*

_{r}. The turbulent kinetic energy in pattern A was mostly contributed by the horizontal fluctuation of flow near the backstep in the recirculation zone, and the region with maximum horizontal fluctuation was found to evolve toward the base as the flow moves downstream. However, the weighting of vertical fluctuation became more significant as the wall injection velocity ratio increased.

**Keywords:** Backstep; Flow pattern; Flow visualization; LDV

An experimental and numerical study of forced convection in a microchannel with negligible axial heat conduction by Guodong Wang; Liang Hao; Ping Cheng (

*pp. 1070-1074*).

*z*=0.15RePrD

_{h}, with the fully-developed Nusselt number approaching a constant value of 4.00.

**Keywords:** Heat transfer; Laminar flow; Microchannel; Microheater; Numerical simulation

Drag reduction and heat transfer enhancement over a heated wall of a vertical annular microchannel by Huei Chu Weng; Cha’o-Kuang Chen (

*pp. 1075-1079*).

**Keywords:** Microfluidics; Natural convection; Rarefaction; Fluid–wall interaction; Annulus

*pp. 1080-1080*).