CFD for Environmental Flows

1. CAD and snappyHexMesh

a. Problem definition

The third problem we work on is a 3D flow over several buildings. See the 3D view of the buildings we use in our computations below.

Figure: CAD model used in this section

Here, learning and reporting the boundary, initial and computational conditions will be your Assignment 3. Details will be given at the end of the section.

b. Pre-processing

Copy the windAroundBuildings tutorial directories

You are going to use the /opt/openfoam10/tutorials/incompressible/simpleFoam/windAroundBuildings tutorial case of OpenFOAM in this section.

First, copy the tutorial case in your local working directory.

cp -r /opt/openfoam10/tutorials/incompressible/simpleFoam/windAroundBuildings ~/OpenFOAM/lecture04/

Uncompress the CAD file

Uncompress the compressed file using

cd ~/OpenFOAM/lecture04/windAroundBuildings
cd constant/geometry
uncompress buildings.obj.gz

Mesh generation

Run surfaceFeatures, blockMesh, and snappyHexMesh -overwrite commands, respectively, as you have done in the previous section for 2D car model to generate the comptuational mesh. Here, the -overwrite option overwrites the snappyHexMesh in 0 (zero) directory. So, you do not need to copy the last mesh from output and remove the unnecessary ones.

c. Computing

Please compute the fluid flow until $t=200~\mathrm{s}$. Use $\Delta t=1~\mathrm{s}$. Write the results for each $2~\mathrm{s}$ of the flow. Use all the other settings as it is given in the related file of the tutorial.

Compute the fluid flow using simpleFoam command.