Week 3: Flow over a backward facing step

Once you have watched the video, setup the case in CONVERGE

Once you have the base setup ready, run the case for three different base mesh sizes

• dx = dy = dz =2e-3 m
• dx = dy = dz =1.5e-3 m
• dx = dy = dz =1.0e-3 m (If this is too much for your PC, use 1.2e-3 m)

Answers

This is a simple basic analysis of fluid simulation through a backward-facing step.

The geometry

For the first, we need to scale-down the the geometry to a scale factor of 0.001

Boundary Definition

As this is a basic problem make this option as default

Global transport parameters - default values

Reaction mechanism

Run Parameters

Simulation time Parameters

Solver Parameter

Regions and Initialization

Turbulence Modeling

CASE 1-

• dx = dy = dz =2e-3 m

Base Grid

We enabled the Fixed Embedding option here

The Boundary conditions

Now we export all the files to a folder.

By using Cygwin we run the simulation using the exported files.

Finally the simulation had ran successfully.

Now, we use Converge to convert the files to ParaView readable files.

Now we open Paraview and load the .vtm group files over there and click Apply

The loaded geometry in Paraview

The Velocity Contour

The Pressure Contour

Line Plot Showing Mass flow rate

Total Cell count

Avg Velocity at Outlet

Static Pressure at Boundary

*******************************************CASE 2****************************************************

Case 2

• dx = dy = dz =1.5e-3 m

RESULTS

Velocity Contour

Pressure Contour

Line Plot showing mass flow rate

Average velocity at Outlet

Total pressure at Outlet

Total cell count

********************************************CASE 3***************************************************

Case 3

dx = dy = dz =1.2e-3 m

RESULTS

Velocity Contour

Pressure Contour

Velocity at outlet Line Plot

Pressure At outlet

Mass Flow rate at the Boundary

Total Cell count.

explain where and why separation is taking place in detail?

The separation of the air flow takes place at the point where the area of the cross-section increases, that is at the edge inside the box