Flow over a backward facing step
The main purpose of this challenge is to simulate a flow over a backward facing step using CONVERGE CFD. The simulation is set up based on the tutorial videos and the only parameters that have been changed are the mesh grid density (number of computational cells) and the total number of cycles.
In the following graphs, we can see the mesh grid, velocity and pressure fields, close-up of the separation area with velocity vectors, velocity profile at the outlet of the channel, mass flow rate and total number of cells for each different mesh case.
A. dx = dy = dz =2e-3m
B. dx = dy = dz =1.5e-3m
C. dx = dy = dz =1e-3m
From the graphs we can observe that the finer the mesh the smoother the graphs are (velocity and pressure fields and velocity profiles). The glyph plots shows that the separation occurs exactly after the step. This happens because there is an sudden increase in the area of the channel (step). As result an adverse pressure gradient in the flow direction appears. This makes the flow particles to slow down, loss their flow momentum and separate.
The following link correspond an animation (one the 3rd case) of the computational solution.