Captive Model Simulation (Pure Yaw and Sway Tests)

In order to perform a "pure yaw" test with Orca3D Marine CFD you will need to follow these steps. Note that this requires the Premium version.

1. Set up your model in Orca3D as a "resistance" analysis as you normally would. You will of course need to use the full model, port and starboard sides, so make sure to check the box for the "asymmetric" simulation in Orca3D.

2. After opening the model in SimericsMP, select the Marine module in the Model tab as shown below. 

a. Change the "Analysis Type" from Resistance/Powering to Planar Motion. 

b. Choose which Dynamic Option you want. In the example below we chose to allow the model to be free in Pitch and Heave. 

c. Then set the Propulsion Option to Static Drift. Specify your Target Velocity and Ramp Up Time for the yaw simulation, then specify the yaw rate you would like to use. Here it was 0.00949 rad/s which is about 0.5 deg/s.

3. Start the simulation and let it run to completion or until the simulation has converged. You can plot the Yaw moment and Sway force as shown below by clicking on the Marine module when making the time history plot.

Creating a pure sway test is very similar. The only difference is that instead of specifying the "Target Yaw Rate" in the Static Drift propulsion option, leave that value at 0 and specify a non-zero drift angle as shown below.