Discussion Forum

Hi, dear ivar,

Duo to the mess before, I decide to do as you said to do it from the very begin. Otherwise I am going to be crazy!

I redraw the graph which is simpler, domain 1 is fluid domain, others 2-5 are used later for plane strain.

If I just set the inlet as normal inflow velocity U0=0.75[m/s], it shows like ok.

But my real boundary conditions are (because it is the valve in our body, so the entrance velocity is periodic)

1. entrance
assume a fully developed parabolic axial velocity u(0,y,t) and v (0, y, t) at the tube entrance, the axial velocity is assumed to be periodic
u(0,y,t)=Um(r(0,t)-y)(r(0,t)+y)
UM=U_max*sin(2*pi*t/Tc) (n-1)Tc<t<(n-0.5)Tc Tc is the period=3s
=0 n-0.5)Tc<t<n*Tc

u_max is the maximum axial centerline velocity and Tc is the time between opening and closing of the leaflet(domain 3)

2. Exit prescribed pressure condition Pd=1000pa

3. Internal boundary of the tube wall
assumed to be the same as the rate of the displacement of internal tube wall in the respective directions.
For here I just assume they are no slip wall to see if the model can work or not.

4. centerline
Symmetric boundary conditions are assumed.

These are the right conditions that after I discussed with my professor. But I really don't know how to put periodic boundary conditions in the model, and I am not sure other boundaries are right or not. so would you please check it for me?

Also I have a small question, the expression u_max*(s+0.5)*(s-0.5), is this a periodic expression, is there any special meaning with 's' in comsol, (from 0-1??)

I will run this model first and then add the moving mesh in 2-5

Thank you for all your help to help me and walk together with me on this difficult comsol road!

Give my bigggest thanks!