CFD modeling of buoyancy driven cavities with internal heat source—Application to heated rooms

Abstract

The aim of this work is to examine the capacity and the accuracy of a CFD (Computational Fluid Dynamics) model to characterize the thermo-aeraulic behavior of a heated room. Firstly, we present a brief description of the experimental setup taken into account. Afterwards, we focus on the main features of our numerical model (that strongly influence the accuracy of results): computational domain geometry and discretization, turbulence model, near wall treatment, radiation model and thermal boundary conditions. In addition, we present here a simplified approach in order to integrate a pure buoyancy source within our model, based on a volumetric heat generation rate (taking into account only the source power and its dimensions) which is uniformly distributed within the heater. Furthermore, detailed experimentalnumerical comparisons are given with regard to heat transfer to the walls as well as to heat source behavior and plume characteristics. The results obtained demonstrate that the CFD method employed in this work leads to reliable results. Consequently, this approach can be useful in detailed studies dealing with thermal comfort, indoor air quality and energy consumption for heated rooms. Finally, the simplified method presented here, concerning the integration of the heat source in the CFD model, can be effortlessly extended for other localized heat sources that differ in power, heat emission mode (convection or radiation), shape or size.

CFD modeling for natural ventilation in a lightwell connected to outdoor through horizontal voids

“…Therefore, two different methods as provided in the solver (ANSYS-Fluent) have been used to represent heat generation in the lightwell that corresponds to those provided in the WTE. The CFD is able to prescribe surface heat flux on the inside surfaces of the lightwell, and by specifying the volumetric rate of heat generation of the lightwell volume [41].…”

Experimental and Numerical Investigation on a Water-Filled Cavity Natural Convection to Find the Proper Thermal Boundary Conditions for Simulations

“…The turbulence terms are also ignored for the laminar flow inside the cold heat exchanger and cavity. A realisable k-ɛ model was employed to simulate the fluctuating velocity and turbulent viscosity, which has been successfully used by some researchers (Bacharoudis et al [28] and Teodosiu et al [29]). The transport equations for the turbulent kinetic energy (  ), dissipation rate (ɛ) and viscosity are briefly presented as follows:…”

The angular discretization impact of thermal radiation computations on heat transfer in rooms

“…Concerning the heat source integration in the CFD model, this is accomplished based on a volumetric heat generation rate which is uniformly distributed within the heater [15].…”