Modeling and analysis of convective heat transfer on rough surfaces

The accurate modeling of rough surfaces has become essential due to the increase in the use of additive manufacturing. This paper uses the Discrete Element Roughness Method (DERM) as a means of modeling heat dissipation via convection. DERM’s underlying modeling of energy, which is coupled with its respective governing energy equation, is applied to a Computational Fluid Dynamics (CFD) simulation. This work implements a hemisphere roughness element as a method of evaluating the DERM energy model through a CFD. Three different mass flow cases were used as case studies for evaluating heat transfer from the hemisphere element. The properties needed to evaluate Reynolds and Nusselts number were extracted and applied to DERM’s heat transfer prediction model; these values are then compared to the CFD heat transfer as a function of height. It is found that deviations exist near the top and bottom 20% of the height of the element. Additionally, heat transfer did not significantly change when changing to an unsteady RANS model.