Accurate and reliable computational fluid dynamics (CFD) simulations are essential for the assessment of Cross-Ventilation of buildings. To determine which CFD models are most suitable, validation studies are required. Therefore, the objective of this simulation is validate a 3D Steady RANS simulation of Cross-Ventilation where the mean flow is resolved whereas the effects of turbulence (fluctuating components) on the mean flow is modeled using turbulence model. The validation is based on the velocity parameter (Vx) and RANS simulation is conducted with the realizable k-e turbulence model.
- Simulate a 3D Steady RANS simulation of Cross-Ventilation using OpenFoam (Platform SimScale).
- Validate the results with a Experimental Data. The validation is based on the Velocity parameter (Vx).
- Compare the results with LES “flow pattern” reproduced by the reference.
The Computational Model represents the reduced-scale model used in the wind-tunnel measurements (13x1.8x1.8m^3) (LxHxW).
One can note that Symmetry Plane was used here in order to save elements number as well time consumption of the Simulation.
The first Computational Grid were created in ICEM CFD (MESH 1) - Full Hexa.
The second one was created in SimScale (MESH2) - Hexa Dominant.
The details of the Computational Grids are shown below.
A good convergence was achieved using realizable k-e turbulence model for both meshes.
- The “SimScale Platform” is used here to solve the approximate forms of Governing Equations (Navier-Stokes).
- The 3D Steady RANS equations are solved in combination with “k-e turbulence model”.
- The “SIMPLE Solver” algorithm is used for pressure-velocity coupling.
- Convergence is assumed to be obtained when all the residuals level reach a minimum value.
Results and Conclusions
The results of Steady RANS CFD simulations with SimScale (OpenFoam) model for two different meshes are presented here.
The results obtained with k-e turbulence model and SIMPLE Solver using SimScale show good agreement with the experimental data, both with respect to the velocities (Vx) for the lines (a, d, g and Mid) and flow pattern (jet direction).
Comparison LES (Reference) Vs. RANS
Below contours of dimensionless mean velocity magnitude obtained with steady RANS CFD (SimScale) and LES Simulation (from the Reference) both in the vertical center plane.
- The LES results above provide a slightly higher velocity magnitude in the incoming jet compared to RANS.
- Th incoming jet is slightly more horizontal in LES than with RANS.
- The spreading of the jet is more pronounced in LES.