Wen-Hsiung Huang’s scientific contributions

Fluid flow and heat transfer characteristics are analyzed for the laminar forced-convection flows in a parallel-plate channel with an array of fins mounted on the wall. The two plates are maintained at uniform but unequal temperatures and the mounted fins are assumed to be perfectly conductive. Numerical solutions for the Reynolds number within the range 10 <= Re <= 300, fin height within , and fin pitch within are presented. Analytical solutions for the infinite and zero pitch cases, representing the lower-bound and upper-bound values, respectively, are developed and compared with the numerical predictions. Results show that both the heat transfer and friction factor (i) increase with the Reynolds number and (ii) are highly sensitive to the geometric arrangements.

The present analysis is concerned with flow reversal phenomena and heat transfer characteristics of the fully developed laminar combined free and forced convection in the heated vertical channels. Three fundamental combinations of thermal boundary conditions on the respective wall surface (namely isoflux-isoflux, isoflux-isothermal, and isothermal-isothermal) are considered separately so as to investigate extensively their distinct influence on the flow pattern. Results of the velocity distribution and temperature distribution as well as the Nusselt number in terms of bulk mean temperature are carried out. Based on the analytical solutions obtained, flow reversal adjacent to the relatively colder wall is found to exist within the channel as Re/Gr is below a threshold value related to the thermal boundary conditions. Parameter zones for the occurrence of reversed flow are presented. Comparisons and verification are made using the existing numerical solutions at locations far downstream of developing flow.

The present study is concerned with the thermal characteristics of free convection in the locally fully developed region within vertical channels. Similar to that in the well-known internal convection channel flow, the flow field may include entrance region and fully developed region simultaneously as channel is long enough. For locally fully developed region, velocity distribution and Nusselt number as well as generalized temperature profiles in terms of bulk mean temperature are carried out analytically by solving the momentum and energy equations. The existence of locally fully developed region is then confirmed numerically with the solutions for developing flow at far downstream. Results for three different combinations of thermal boundary conditions on the respective wall surfaces (i.e. isothermal-isothermal, isoflux-isothermal), and isoflux-isoflux) are provided to extensively illustrate the substantial influences of heating conditions with closed-form expressions.

This study is concerned with the prediction of the generation of entropy as well as heat transfer characteristics of the two-dimensional laminar forced-convective flows within channels, onto whose walls one or two pairs of transverse fins are attached symmetrically. These fins, placed in the entrance regions of the channels, interrupt the development of the boundary layers, and result in changes of thermal performance and viscous friction. Consequently, local irreversibilities increase significantly due to the existence of the fins. Solutions of the elliptic momentum and energy equations are carried out through the stream function-vorticity analysis. Distribution of the entropy generation can be further obtained from the velocity and temperature solutions by solving the entropy generation equation. A co-ordinate transformation technique1,2 has also been employed in the present computation for the treatment of boundary conditions far downstream. Both walls of the channel are maintained at a constant temperature. Two limiting situations for fin properties, namely perfectly conductive and adiabatic, are considered. Results for various geometric arrangements under different Reynolds numbers are presented. A comparison of results for the finned and unfinned channels has also been carried out.

The present analytical study is concerned with the thermal characteristics of hydrodynamically and thermally fully developed flow in an asymmetrically heated horizontal channel, which is divided into two passages (by means of a baffe) for two separate flow streams. Each stream will have its own pressure gradient and hence its own individual velocity profile. Based upon bulk mean temperature of the whole flow in the channel, Nusselt numbers and the generalized temperature profiles in the fully developed regions are determined by means of integration of the momentum and energy equations. Three possible combinations of the thermal boundary conditions on the two wall plates of the channel are considered: isothermal-isothermal, isothermal-isoflux, and isoflux-isoflux. Results show that the thermal characteristics of the fully developed flow could be significantly affected by the position of the baffle, the pressure-gradient ratio by the two separate streams, and thermal boundary conditions on the channel walls.

A numerical study was done for laminar fluid flow and forced convection heat transfer within horizontal channels to which one or two pairs of transverse fins are attached. Solutions of the elliptic equations are carried out through the stream function-vorticity analysis. A coordinate transformation technique was used for the valid treatment of boundary conditions at the far downstream zone. Both walls of the channel are maintained at a constant temperature. Since the thermal boundary conditions on the fin surfaces depend on the conductivity of the fin material, the limiting situations for fins, perfectly conductive and adiabatic, are both considered in order to investigate their effect on the flow. Results for different Reynolds numbers and various geometric arrangements are obtained. In addition to the velocity, temperature, and vorticity distributions, local heat transfer performance is evaluated, and a comparison of the results between the channels with and without transverse fins is also made.

This paper is concerned with the numerical study of the heat transfer characteristics of the laminar mixing flow within a vertical channel. Free convection flows are induced by buoyant force from the subchannels and mix upward in the downstream main channel. The parabolic boundary layer equations are solved to obtain the velocity, temperature, and pressure distributions for the whole flow field, as well as Nusselt numbers along the plate walls. In the computation, the parallel side walls are considered isothermal and heating is symmetric. Results for both isothermal and isoflux central plate cases are presented. The mixing phenomena are investigated, and the influence of the central plate on the heat transfer performance is also evaluated.