FSI-RK2 about trainingtracks HOT 5 CLOSED

Hi, this code allows to limit Y displacement of the sphere.

Y_.first() - Position
Y_.second() - Velocity

You don't need to modify your RK2 solver if your object starts to move from point different to (0 0 0)

from trainingtracks.

Thank you. One thing more to clear: If the object start to move from an arbitrary position (i.e. Xc, Yc), not from (0 0 0), then how and what part to modify? Where Xc = 0.5, Yc = 0.5 or any value other than 0.

from trainingtracks.

Hi, sorry for the late reply.
If Xc = Yc = 0.5, then:

1. Center of the object in your mesh must be in the poing (0.5; 0.5)
2. Yold_.first() = 0.5 at startup

from trainingtracks.

Thank you for the reply.

Sorry, I forget to mention about my domain boundaries, they are [0,0] to [10,10]. Normally, the above is true when domain is extended in both positive and negative directions e.g [-1,-1] to [1,1]. In my case, the rest length for the spring (-kx) will be different that what I am confused with. What will be the "Yold_.first() or Ymid.first()" in the equation:

Ymid.second()= Yold_.second() + 0.5*dt*(-C_*Yold_.second() - K_*Yold_.first() + R_*yForce) / M_;
Y_.second()= Yold_.second() + dt*(-C_*Ymid.second() - K_*Ymid.first() + R_*yForce) / M_;

I have attached an illustrative image to clear my point and want to modify the equations according to the sketched situation.

from trainingtracks.

Hi, you don't need to change equations. Equations describes numerical solution of some ODE from some initial position.
Just initialize your Yold_.first() with 5.0 in the class constructor or somewhere, where are you creating variable and reading data

from trainingtracks.