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Moritz
Posts:
8
Registered:
5/24/13


using solution of previous time step for DAE dde23 applicable
Posted:
Sep 24, 2013 10:59 AM


Dear all,
i do have a PDE which describes sedimentation. I do discretize it in space and end up with a system of ode´s. Fairly simple.
Now i use the same PDE (settling of particles) inside a syringe (no particles leave the syringe) and move the piston (pressure filtration). Therefore i do have a moving boundary at the piston. So i have to solve for the piston height too. One boundary is in fact an algebraic equation.
The system looks like solving for the piston height:
dh/dt=(height(n+1)height(n))/dt = someODE
i=1 (Algebraic equation for boundary) y(i) =h(n)/h(n+1)*(something) i=2:N dy/dt= dh/dt*(something discretized) + h(n)/h(n+1)*(something discretized)
My question is if i can use dde23 here or not ? I do have a published method with euler timestepping and i would like to use the comfort of a variable time stepping routine. ode23 works well for the simple cases with MOL.
Sincerly
Moritz



