Fan boundary condition

Download mesh

Download simulation

Introduction

This problem involves predicting the airflow in a room with two fans. The fan geometry is simplified to a circle and fan boundary conditions are used using performance curves.

Start BaramFlow and load mesh

Run the program and select [New Case] from the launcher. In the launcher, select [Pressure-based] for [Solver Type] and [None] for [Multiphase Model].

Use the given polyMesh folder. In the top tab, click [File]-[Load Mesh]-[OpenFOAM] in that order and select the polyMesh folder.

The mesh is created by baramMesh. The directions of the flow through the fans are determined by the direction of the surface normal vector of fan. The normal vectors of the two fans are shown in the figure above. When preparing the geometry file, you should check the normal vectors and align them in the desired direction.

General

For this example, we’ll use default conditions.

Models

For this example, we’ll use standard $k-\epsilon$ model for turbulence.

Materials

Use material properties of air.

Boundary Conditions

For the boundary conditions, use the Fan condition for fan1 and fan2 and set up a Fan P-Q Curve file (download file). The Fan P-Q Curve file is a csv file with the first column being velocity and the second column being pressure.

  • fan1 : fan
    • Coupled Boundary : fan1_slave
    • Fan P-Q curve file : UvsP.csv
  • fan2 : fan
    • Coupled Boundary : fan2_slave
    • Fan P-Q curve file : UvsP.csv
  • All others : wall

Numerical Conditions

Set [Discretization Schemes] of Turbulence as [Second Order Upwind].

Use default values for the rest.

Initialization

Set initial value as below.

  • Velocity : (0 1 0)
  • Pressure : 0
  • Scale of Velocity : 1
  • Turbulent Intensity : 1
  • Turbulent Viscosity Ratio : 10

Run

Change the values as shown below, and click [Start Calculation] button.

  • Number of Iterations : 3000
  • Save Interval : 100
  • Selct [Parallel]-[Environment] in menu. Set Number of Cores as you want and select [Local Machine] for [Parallel Type].

When the calculation is started, you can see the graphs of Residuals as shown below.

Post-processing

Click the parview button in [External tools] to open the paraview.

For parallel case, change the [Case Type] to [Decomposed Case].

 Click [Slice] icon.

In the Pipeline Browser, select [Z Normal] and set 1 at z-coordinate.

Choose [Coloring] as [U] and set [Representation] as [Surface LIC]. Then you should see something like this