Setting Initial Conditions

Training Guide > Compressible Flow Tutorials > Transonic Flow over an Airfoil > Setting Initial Conditions

Setting Initial Conditions

The initial velocity field will apply free-stream conditions across the entire domain, i.e. a velocity of 247.967 m/s calculated using the equation:

(1)

where , , and

To specify an angle of attack of 2.54^ofor the initial velocity, we will create a new coordinate system.

Open the Tools node at the bottom of the simulation tree and right-click the Coordinate Systems node.

Select New > Cartesian Coordinate System.

A node called Cartesian 1 will be created within the Coordinate Systems node.

Select the Cartesian 1 node and, in the Properties window, change the X Axis Direction to that shown below:

[0.9990, 0.0443, 0.0]

When you enter these coordinates, the Y Axis Direction will change automatically to ensure that the axes are perpendicular. The X Axis Direction will also readjust itself slightly. The resulting Properties window is shown below.

This now defines a coordinate system that, when viewed down the +z-axis, has its x- and y-axes rotated anti-clockwise through an angle of 2.54^o compared to the laboratory system.

Return to the Aerofoil continuum node and select the Initial Conditions > Velocity node.

In the Properties window, change the Coordinate System property to Cartesian 1.

Select the Velocity > Constant node.

In the Properties window, change the Value to [247.967, 0.0] m/s.

To specify the initial temperature:

Select the Static Temperature > Constant node.

In the Properties window change the Value to 291 K.

The default values for the remaining initial conditions are suitable for this problem.

Save the simulation.

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