Author(s): Sebastian Vecchi, ANSYS Inc.
Problem Specification
1. Pre-Analysis & Start-Up
2. Geometry
3. Mesh
4. Physics Setup
5. Results
6. Verification & Validation
Physics Set-Up
Create New Material
In the problem specification, a density and viscosity are defined for the fluid flow that do not match those of air or water. A new material must be defined with the properties that we wish to have. Select Material Assignments and in the Material drop down menu choose Create New.
The problem specification did not define whether the fluid was a liquid or gas, but since the density and viscosity were defined, it does not matter. Press Add next to either Liquid or Gas Properties. In the drop down menu, choose Density and input 1 [kg m^-3]. Do the same to define the Viscosity as 0.05 [kg m^-1 s^-1], or 0.05 [Pa s]
Boundary Conditions / Forces
First, the inlet must be defined using the Fluid Flow Conditions. In the Add drop down menu by Fluid Flow Conditions, select Inlet. Then, using the Face selection tool, define an inlet at the end closest to the cylinder. Make sure to input the Velocity magnitude as 1 m/s.
Once the inlet is defined, the outlet is next. In the same menu, use the Outlet condition to define an outlet at the end of the enclosure farthest from the cylinder. Assign a Gauge static pressure of 0 psi.
Add a Symmetry condition from the Add drop down menu to the side faces of the flow volume.
A free slip wall condition must be created in order to channel the air inside of the enclosure, much like one would find in a wind tunnel. Select the Wall condition from the Add drop down menu and apply it to the top and bottom of the enclosure, then change the Option under Flow Specification to Free slip.
Next, a Wall condition must be added to all surfaces that are not already defined. Most of the time, AIM will automatically create the walls once the option is selected; AIM selects every face that doesn't already have a constraint on it.