You can add a wind velocity to the simulation. It is not built into the marine template currently so you need to do it manually. Note that if your wind direction is other than directly ahead or directly behind the vessel, your analysis is asymmetric and should be set up that way in Orca3D.
1. After loading your model into SimericsMP select the "Marine" module in the Model window and in the Properties window change the Setup Options from "Template Mode" to "Extended Mode".
2. Click on the little "A=?" icon in the upper right corner of the Properties window (or in main toolbar) to open the Expression Editor. Inside of the expression editor add the following lines. Note that the direction of the wind is related to the positive X and Y directions in your Simerics model as indicated by the coordinate axis gnomon in the view.
windSpeed = 10 # m/s
windSpeedHt = 10 # m, reference height
windDirection = 45 * pi/180 # in radians, 0 is head wind for this example because +X points aft
windGradientSpeed = z>0 ? windSpeed * (z/windSpeedHt)^(1/7) : 0
windGradientSpeedVec = [windGradientSpeed * cos(windDirection), windGradientSpeed * sin(windDirection), 0]
3. In the Geometric Entities window under "Volumes" select the "marine" volume. Then in the Properties window expand Flow > Mixture > Initial Condition and set the Velocity to be "windGradientSpeedVec". This sets the initial condition for the simulation to have the wind velocity inside the volume at time 0. Depending on the version of SimericsMP you are using, you might find that this Initial Condition is non-editable and thus can't be changed from its default value. If that is the case it is OK to continue to the next step without completing this step. This just means that instead of the simulation starting with a wind velocity throughout the entire fluid domain at the first time step, the wind defined on the inlet of the domain will have to propagate across the domain before there is a steady wind flow. Usually this should happen prior to the simulation reaching steady body dynamics and a steady water flow field, so it should not present a problem.
4. Now we need to set the boundary conditions so that we continue to have that flow velocity while the simulation is running. In the Geometric Entities window select the four marine boundaries for an asymmetric run (3 for a symmetric) run representing the front, back, port side, and stbd side. (don't select the symmetry plane although if you have any cross wind it becomes an asymmetric problem). Under Flow > Velocity Profile > Back Flow Velocity set the vector to be "windGradientSpeedVec".