The Buongiorno model is used to investigate the effects of Brownian motion and thermophoresis on the flow, heat, and mass transfer from a flat plate with prescribed surface heat flux. The experimen...

This article documents the results of an investigation into aspects of the simulation and modeling of turbulent jets that impinge orthogonally on a target surface. The focus is on the case of a jet which issues from a circular pipe into stagnant surrounding at the relatively high value of Reynolds number of 23,000 (based on nozzle diameter and bulk velocity) for which experimental data are available. Large-eddy simulations were performed to obtain details of the mean flows and the turbulence fields including distributions of all components of the turbulent heat fluxes. The outcome of these simulations were used to assess three alternative models for the turbulent heat fluxes which differ from the conventional Fourier's Law by not being based on the assumption of proportionality between the eddy and thermal diffusivities via a constant Prandtl number. It was found that only one of the models considered succeeds in representing the effects on the heat fluxes of the complex strain field associated with the stagnation region and the subsequent development into the wall-jet region. The reasons for this outcome are discussed.

In this article, the heat transfer augmentation on a flat surface with jet impingement on axisymmetric detached ribs is numerically investigated. Both single and multiple jet impingement with and without crossflow interaction is investigated. Numerical simulations are done using Reynold-averaged Navier–Stokes (RANS) equations with a shear stress transport (SST) model with the commercial CFD code ANSYS-CFX. The influence of jet Reynolds number (7000 ≤ Re _j ≤ 78,000), blowing ratio (5.8 ≤ M ≤ 11.5), and jet-outlet-to-target wall distance (2 ≤ H/D ≤ 6) are examined. Results show that the heat transfer is enhanced on the target wall with detached ribs in single and multiple jet impingement at moderate crossflow speeds.