Is it possible to model air/fluid density in a simscape model?

I'm trying to develop a model for an underwater system and I was wondering if there was a way to model hydrodynamic effects (buoyancy/disturbances/inertia etc) using Simscape?

Answer 1

[Nicolas Schmit]

Simscape Multibody (Sim Mechanics) does not model the environment around your system, except for the gravity acceleration. To include hydrodynamics effects you can use the External Force and Torque bloc. For example, buoyancy would be a constant upward force (in the world reference frame) depending on the geometry of the solid and the mass of the surrounding fluid.

[K F]

Thanks Nicolas! Using the external force and torque block for buoyancy is a useful tip. So if I was to model a rigid body underwater, I would have to apply the added inertial matrices (e.g. added inertia of a fluid and body-water drag forces) from first principles (i.e. simulink block/matlab function)?

[Nicolas Schmit]

Hello. Yes, you could use a Simulink model or MATLAB function bloc to calculate the force, then convert the force to a physical signal using a Simulink/PS bloc, and input the signal to the External Force and Torque Bloc. Be careful to select the correct reference frame to resolve the force, depending if you calculate the force in the world frame or in the solid's frame.

[K F]

Thanks very much for your help.