So I have some confusions about the hydrostatic elements (HSFLD241 or HSFLD242). I understand that these elements have displacement DOF and an extra node that take care of the pressure DOF and by defining the location of the pressure node we can have positive or negative volume (or area for 241). So the first thing that I do not understand is the use of positive and negative volume. Is it only to say that there is mass in the positive volume and no mass in negative volume or does this + or – volume can change the pressure distribution. Let me explain my problem to make it more clear.<\/p>\n
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I have a simple cubic domain that has a spherical cavity inside it. In reality, this spherical cavity is filled with water which is incompressible but because I do not want to link my static structural modeling to fluent, I used HSFLD242 elements that are designed for this type of situation. Since the volume of the sphere is very small, I do not care about pressure change as we go more inside the fluid. So the pressure is completely uniform in the sphere. I also do not want to give initial pressure to the water. Now the solid domain deforms (large deformation) and due to that, the sphere will deform to something like an ellipsoid. Do I need to care about the + or – volume of the HSFLD242 elements (especially that I chose keypoint(5)=0 for HSFLD242 which means that there is no mass of fluid)? can this strategy accompany with keypoint(6)=1 capture a physics that volume is not changing but the pressure of the fluid will change?<\/p>\n
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So my main issue is that my geometry is not simply a sphere and it is a convex geometry as I mentioned in:<\/p>\n
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\/forum\/forums\/topic\/self-contact-problem\/<\/p>\n
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So there is no way that I can simply define my HSFLD242 elements with only one fluid pressure node and get positive volume everywhere. So I am wondering if the + or – volume matters or not for this problem. If it matters, how can I use HSFLD242 for a convex geometry while we now that there exist fluid everywhere in the cavity even if the volume goes out of the cavity?<\/p>\n
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