Asymmetric Results from Symmetric Setup

Hi there,

An assignment from the course asks me to explore how wind velocity looks like in an ideal block in Solidworks Flow Simulation. The graph posed below is a looking-down view, as four grey building studs make a block. Wind is blowing from left side only, and all other setups that I am aware of are symmetric, but the velocity field is not symmetric at all, as shown in the graph shown below. I am trying to figure out what makes the simulation asymmetric with symmetric setups. Wondering if anyone can help me out

Here are some setup details:

  Computational domain is 40m*40m*15m

  Block consists of 4 buildings, each of which is 10m*10m*10m

     Each building is 10 m away from another closest building, and the building edge is 5 m away from the computational boundary

  Fluid is air as external flow

  Wind enters horizontally the domain only from the left boundary at the velocity of 6 m/s

Please let me know if any other detail is needed. Thank you!

SolidworksFlow Simulation