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Simulating fluid structural interaction, without the structural part?
Posted 29 feb 2012, 09:22 GMT-5 Fluid & Heat, Modeling Tools & Definitions, Parameters, Variables, & Functions Version 4.2a 2 Replies
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In order to learn more about the pump, and also comsol, I want to first forego simulating the mechanical part.
What I would like to do is: model a reservoir with two open boundarys and see how the fluid flows if I change the shape of one wall of the reservoir. This wall is the membrane. At this moment, I am not interested in the structural properties of he membrane. I want a prescribed movement of that wall. which will be in the form a squared sine function. So I want the shape of the wall to change over time. (vibrate) and see how this influences the liquid in the reservoir.
It is not the same as doing a parametric sweep and changing the model shape. This just reruns the same simulation with a different shape, it doesn't 'remember' the previous condition with respect to conservation of mass.
An alternative is to model the membrane wall as an inlet and applying a varying inflow velocity. This is okay, but it doesn't show in the graphs that I'm actuall changing the shape of the membrane.
Any suggestions on how to simulate this? Will I need to use FSI?
Many thanks for any suggestions.
-Jaap
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you could try an ALE + SOLID + SPF (in that order), with an imposed varying pressure on the membrane = SOLID, ALE over the fluid domain to take into account the SOLID deformation and SPF for the fluid flow
FSI is perhaps an overkill since you are going the other way around: solid to fluid and seem not to care about the dynamic forces of the fluid on the solid
--
Good luck
Ivar
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ale+solid+spf seems to me exactly like fsi, as it is a combination of solid deformation and flow
I'm only modeling the fluid so I wouldn't know where to set the solid conditions on.
Could I just do it with ALE and SPF? The ALE deforms the mesh, the spf would calculate the flow to fill the new volume?
I've tried to model a simple 2D system with a square reservoir, one wall is bending up and down by applying a prescribed mesh displacement in the DG (or ALE), another wall is the outlet. That's all I've set.
I can get the ALE or DG to do what I want, but when I add SPF, it doesn't really calculate anything with respect to the original condition. So there is no flow nor pressure difference. It just considers each shape as a new mesh.
It's probably what you said about having the SOLID calculate a pressure over one of the walls. But I dont understand how I would use SOLID to calcualte the change in pressure due to the change in shape. Would I be able to set the pressure of the fluid as a function of the difference in shape with the last geometry?
Your help is much appreciated.
-Jaap