Mixed convective heat transfer from a heated sphere at an arbitrary incident flow angle in laminar flows

Abstract

The mixed convection from a heated sphere for an arbitrary flow incident angle (θ) at low to moderate Reynolds numbers () and Richardson numbers () is studied by an immersed boundary method, thereby investigating the influence of different flow incident angles () on the buoyancy flow and heat transfer. The numerical method is validated by comparing the results with the simulation results of pure forced convection as well as those of mixed convection with assisting flow (0 o flow incident angle) published in the literature. Extensive simulations for a wide range of different incident flow angles have been performed. New correlations are obtained for the overall Nusselt number (Nu) in terms of θ and Ri, and Re, showing a quadratic decrease in Nu with respect to θ only for (aiding and cross flow) and a half bell-shaped decrease in Nu for (opposed flow). The combined treatment of mixed convection for the completely upward flow, cross flow, and completely downward flow (i.e. at incident angle 0°, 90° and 180°, respectively) was achieved showing almost linear relationships between the heat transfer rates and Ri for .

Non-monotonic transport mechanisms in vertical natural convection with dispersed light droplets

“…Specifically, our test set-up is a laminar flow over a rigid sphere which is held at a constant temperature () and is hotter than the free stream temperature (), see figure 2( a ). Here, the gravity vector opposes the free stream velocity and the resulting buoyancy flux is ‘assisting’ the flow (Kotouč, Bouchet & Dušek 2009; Musong & Feng 2014). The flow is periodic in - and -directions and an outflow, radiation boundary condition is prescribed at the outlet for velocities and temperature.…”

“…Therefore, instead of (2.8 a , b ), we employ a more straightforward approach by directly integrating the immersed boundary thermal and hydrodynamic forcing terms over the Eulerian grid points associated with the Lagrangians, i.e. where and (Breugem 2012; Musong & Feng 2014; Wang et al 2019). Here, is the forcing volume associated with each Eulerian point and is equal to the Eulerian cell volume.…”

“…Breugem 2012;Musong & Feng 2014;Wang et al 2019). Here, ΔV k is the forcing volume associated with each Eulerian point and is equal to the Eulerian cell volume.…”

Computational Study of the Coupled Mechanism of Thermophoretic Transportation and Mixed Convection Flow around the Surface of a Sphere

“…They observed that the effects of thermophoresis are dominant as compared with thermal and mass diffusion. Musong and Feng [15] proposed the problem of heat and fluid flow about a heated sphere by incorporating the different ranges of the Richardson as well as the Reynolds' number. They found that the relationship between the heat transfer rate and the Richardson number is very linear for wide ranges of arbitrary incident flow angles in the laminar flow regime.…”

Analysis of mixed convection past a heated sphere

“…In order to predict the effect of particle fluid temperature difference on the wake and the heat transport, they reported their findings in terms of Richardson number for a given Reynolds number. Musong and Feng 29 conducted numerical simulations using an immersed boundary method to investigate the mixed convection from a heated sphere for upward flow, cross flow, and completely downward flow cases. Mixed convection from heated sphere at small Reynolds and Grashof numbers in cross, assisting, and opposing flows studied experimentally by Ziskind et al 30 and Mograbi et al 31 From the extensive literature review as presented above, it can be highlighted here that emphasis has been laid by the researchers on the effects of different influencing parameters such as Reynolds number, drop surface temperature, and Prandtl number on the thermo-fluidic transport characteristics.…”