Analytical solutions of fluid flow and heat transfer in a partial porous channel with stress jump and continuity interface conditions using LTNE model

• Published in: International journal of heat and mass transfer Vol. 128; pp. 1280 - 1295
• Main Authors: Li, Qi, Hu, Pengfei
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.01.2019; Elsevier BV
• Subjects: Analytical solution; Computational fluid dynamics; Continuity (mathematics); Convective heat transfer; Darcy number; Fluid flow; Forced convection; Heat flux; Heat transfer; Local thermal non-equilibrium; Mathematical models; Nusselt number; Partially filled porous media; Porous materials; Porous media; Pressure drop; Stress jump condition; Stresses; Thermal conductivity; Convective heat transfer; Local thermal non-equilibrium; Stress jump condition; Partially filled porous media; Analytical solution
• ISSN: 0017-9310; 1879-2189
• DOI: 10.1016/j.ijheatmasstransfer.2018.08.132

•Effect of the stress jump at the interface on the fluid flow and heat transfer performance is presented within a partial porous channel under local thermal non-equilibrium (LTNE) model. The stress jump is found to have a no noticeable effect on Nu number for both LTE and LTNE models.•Three types of relations between Nusselt number and hollow ratio are observed under LTNE assumption.•Exact solutions are obtained for velocity, pressure drop, the fluid and solid temperatures and Nusselt number. Forced convection heat transfer is analytically performed in a channel partially filled with porous media located at two inner walls under local thermal non-equilibrium (LTNE) condition. A constant heat flux is imposed at the channel walls. The Brinkman extended Darcy model is applied in the porous region and the stress jump and continuity conditions are employed at the interface. Exact solutions are obtained for velocity, pressure drop, the fluid and solid temperatures and Nusselt number. The effects of pertinent parameters on the fluid flow and heat transfer are conducted. Furthermore, the solution for the Nusselt number is compared to that by applying the local thermal equilibrium (LTE) assumption and the validity of the LTE is examined. It is shown that by applying LTNE model for different solid to fluid effective thermal conductivity ratios (K) and Biot numbers (Bi), the variations of Nusselt number with hollow ratio include three types of curves, which are: a maximized Nusselt number occurs at a small optimum hollow ratio, Nusselt number monotonically decreases by increasing hollow ratio and a minimized Nusselt number occurs at a small hollow ratio, respectively. For high K, a small critical value of S at which the Nusselt number reaches to LTE Nusselt number occurs and it lowers with the increase of Bi number and the decrease of Darcy number; while for low K, the LTNE Nu number versus hollow ratio is almost the same with LTE Nu number and therefore the LTE is valid. The stress jump at the interface is found to have negligible effect on the Nusselt number and the pressure drop, except in a high Darcy number with a low stress jump coefficient where the calculation of pressure drop need to account for the stress jump effect at the interface and the Nusselt numbers for both LTE and LTNE models slightly differs from the case of stress continuity interface condition.