In the Standard version of Orca3D Marine CFD, where you don’t have the ability to move any control surfaces on the foil to manage the heave and pitch of the vessel, you can instead run a simulation with the vessel on the foils by prescribing a heave value, removing pitch dynamics, and then evaluate the resulting vertical force and pitching moment.
Two approaches are described; the first is appropriate if the vessel will only heave during the simulation; the second allows you to pre-position the vessel at the roll, heave, and pitch that you want to use in the simulation.
In either case, the foils should be given the face type "Appendage." It is important that the CAD mesh geometry for the foil is sufficient to capture the flow and high pressure concentration near the leading edge. While the default surface meshing in Orca3D Marine CFD is generally well-suited to the hull analysis problem, it may not be for the foil problem. In the example below we've increased the mesh density to accurately capture the leading edge shape around the foil and the tip bulb. You get to the Mesh Settings by click on Options in the CFD dialog, and then the Adjust Surface Mesh button. Remember that this mesh is what is used by Simerics when it is creating the CFD grid; the CFD grid will only be as good as your CAD mesh. Having a very dense mesh does not mean that your CFD grid will have a lot of cells, only that it will be a more accurate representation of your model. This page gives a good description of the various parameters: https://docs.mcneel.com/rhino/7/help/en-us/index.htm#commands/mesh.htm
Heave Only
Set up the simulation in Rhino/Orca3D just as you would any other simulation. Float the vessel using the weight/CG or sinkage/trim, so that the vessel floats as it would at rest. If the simulation is asymmetric, be sure to check the box for an Asymmetric Run.
Now, load the file in Simerics. The first step is to limit the dynamics to "Heave Only." Select the Marine module, then in the Properties pane change the Dynamic Option to Heave Only.
Next, change the Heave Motion Type to Prescribed, and enter a Heave Displacement that represents where you think the vessel will ride when it is foil-borne. Select the marineHeave module, and then change the Motion Type to from Force Balance to Prescribed. Next, enter the Displacement (1m in the example below):
When the simulation starts, there will be a lot of disturbance in the water surface as the vessel "leaps" out of the water to the height that you prescribed, but this will settle out over time.
To view the results, create a new plot window. Select all of the Boundaries (e.g., Hull, Deck, Transom, and Appendages), and plot the Torque Y to see the pitching moment (after selecting Torque Y, click the summation icon in order to see the summed torque for all of the boundaries). Do the same for the Shear Force Z and Pressure Force Z to see the vertical force. Remember that you can copy this data to the clipboard by clicking on the yellow icon in the plot window toolbar.
Roll, Heave, and Pitch
In Rhino/Orca3D, move the vessel into the orientation that you want to simulate, so that Z=0 is the waterplane (that is move it up, and pitch and heel it as appropriate). You will need to know the coordinates of the center of gravity in this new position.
In the CFD setup dialog, select Float Plane and enter 0 for the Model Sinkage, Trim, and Heel. When you click Float, you'll notice that the Displacement and CG are not correct. Complete the rest of the setup as you would for any other simulation.
Be sure to check the Asymmetric Run box if the model is not symmetric about the centerplane. Now check the box for "Create Run Files Only" and click Create Files.
Open the resulting .spro file from your Project Path, and enter the correct displacement, lcg, tcg, and vcg. Save the file, and open it in SimericsMP.
The next step is to turn off the Pitch and Heave Dynamics. Select the Marine module, and then in the Properties pane change the Dynamics option from Pitch & Heave to No Dynamics:
To view the results, create a new plot window. Select all of the Boundaries (e.g., Hull, Deck, Transom, and Appendages), and plot the Torque Y to see the pitching moment (after selecting Torque Y, click the summation icon in order to see the summed torque for all of the boundaries). Do the same for the Shear Force Z and Pressure Force Z to see the vertical force. Remember that you can copy this data to the clipboard by clicking on the yellow icon in the plot window toolbar.