Flow over an Airfoil- Step 5

Step 5: Solve!

Solve > Control > Solution

Take a look at the options available.

Under Discretization, set Pressure to PRESTO! and Momentum to Second-Order Upwind.

Click OK.

Solve > Initialize > Initialize...

As you may recall from the previous tutorials, this is where we set the initial guess values (the base case) for the iterative solution. Once again, we'll set these values to be equal to those at the inlet (to review why we did this look back to the tutorial about CFG programs) . Select farfield1 under Compute From.

Click Init.

Solve > Monitors > Residual...

Now we will set the residual values (the criteria for a good enough solution). Once again, we'll set this value to 1e-06.

Click OK.

Solve > Monitors > Force...

Under Coefficient, choose Lift. Under Options, select Print and Plot. Then, Choose airfoil under Wall Zones.

Lastly, set the Force Vectorcomponents for the lift. The lift is the force perpendicular to the direction of the freestream. So to get the lift coefficient, set X to -sin(1.2°)=-020942 and Y to cos(1.2°)=0.9998.

Click Apply for these changes to take effect.

Similarly, set the Force Monitor options for the Drag force. The drag is defined as the force component in the direction of the freestream. So under Force Vector, set X to cos(1.2°)=0.9998 and Y to sin(1.2°)=0.020942 Turn on only Print for it.

Report > Reference Values

Now, set the reference values to set the base cases for our iteration. Select farfield1 under Compute From.

Click OK.

Note that the reference pressure is zero, indicating that we are measuring gage pressure.

Main Menu > File > Write > Case...

Save the case file before you start the iterations.

Solve > Iterate

Make note of your findings, make sure you include data such as;

What does the convergence plot look like?

How many iterations does it take to converge?

How does the Lift coefficient compared with the experimental data?

Main Menu > File > Write > Case & Data...

Save case and data after you have obtained a converged solution.

Go to Step 6: Analyze Results