[Petrov]

So I want to simulate a rectangle falling through a fluid. (2d) I am going to start the rectangle with a zero initial velocity, and then as gravity acts on it, it will accelerate (which will be simulated by adding a force to the fluid, since I am in the reference frame of the rectangle), and the velocity will increase. At each timestep, I will integrate the force from the pressure (neglecting viscous terms) to find the force on the rectangle and the torque. Then I will update the angular velocity and velocity, etc..

For a given angular velocity and acceleration, I will have to add some correction force because I am in a non-inertial reference frame. How do I find the force? Do I need to change the mass matrix? (I have seen this done, but I'm not sure if it applies in this case)

[cfdnewbie]

Hello Petrov,
just a quick question for clarification:
you say you are simulating a rectangle falling through a flow field.... however, if you add the gravitational force to the fluid (not the rectangle), your flow will be accelerated downwards, while the rectangle stays in place....so in terms of the rectangle, it will not fall, it will rise up....

Or am I mistaken?
cheers :=)

newbie

[Petrov]

Oh, right!

The gravity goes on the object... and the fluid too. That's how real life works, no?

And I figured out the corrections required.. it comes from:
http://en.wikipedia.org/wiki/Rotating_reference_frame

[cfdnewbie]

Originally Posted by Petrov

Oh, right!

The gravity goes on the object... and the fluid too. That's how real life works, no?

Yeah, hopefully so

cheers!