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Please help: 3D model of an elastic (collapsible) thin walled tube with fluid flow (3.5a)
Posted May 19, 2012, 6:08 p.m. EDT MEMS & Nanotechnology, MEMS & Piezoelectric Devices Version 3.5a 1 Reply
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Hi Everyone,
I am working with with two other engineering students trying to create this model for some of our school faculty.
Our final goal is to output a output a force - displacement curve. The model should show the deformation of the vessel walls as the fluid flows through it.
Our variables are internal flow rate ( affecting internal pressure in the tube ) and external pressure.
We created the internal flow rate just by doing boundary conditions of high pressure in ( 2989.0 [N/m^2] ) and zero pressure out. Our fluid is just water (density = 995.7 [kg/m^3] , viscosity = 0.789 Pa*s)
The dimensions of our tube are 6.35E-3m inner (lumen) diameter, 7.32374E-3m outer diameter, (wall thickness = 3.96875E-4 m)
Modulus of the tube wall is 0.8MPa, Poisson's ratio = 0.5.
Our model is for some reason saved as a .m file and we cannot figure out how to open it in COMSOL. I attached the .m code if that will help anyone understand our model, if not please ignore it.
We could only get a velocity profile to show up, but couldn't get any stress values to appear on the walls.
any help would be very appreciated. We need help with every aspect of it, including which physics to use, how to model the fluid flow, and the vessel deformation, and how to couple the two.
Thank you everyone
I am working with with two other engineering students trying to create this model for some of our school faculty.
Our final goal is to output a output a force - displacement curve. The model should show the deformation of the vessel walls as the fluid flows through it.
Our variables are internal flow rate ( affecting internal pressure in the tube ) and external pressure.
We created the internal flow rate just by doing boundary conditions of high pressure in ( 2989.0 [N/m^2] ) and zero pressure out. Our fluid is just water (density = 995.7 [kg/m^3] , viscosity = 0.789 Pa*s)
The dimensions of our tube are 6.35E-3m inner (lumen) diameter, 7.32374E-3m outer diameter, (wall thickness = 3.96875E-4 m)
Modulus of the tube wall is 0.8MPa, Poisson's ratio = 0.5.
Our model is for some reason saved as a .m file and we cannot figure out how to open it in COMSOL. I attached the .m code if that will help anyone understand our model, if not please ignore it.
We could only get a velocity profile to show up, but couldn't get any stress values to appear on the walls.
any help would be very appreciated. We need help with every aspect of it, including which physics to use, how to model the fluid flow, and the vessel deformation, and how to couple the two.
Thank you everyone
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1 Reply Last Post May 20, 2012, 9:03 a.m. EDT
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Posted:
1 decade ago
Hi
first when you save with 3.5a, you can choose the format, m files can only be openend thereafter in a Matlab linked to COMSOL. So it's often better to save the file inthe COMSOD standard format ".mph"
THen one comment, you should avoid a Poisson modulus of 0.5 tha is not really physical, you can use 0.49 if you really want such a high value, I know some polymer or rubbers tend to have a high Poisson ratio, but take a closer look to what 0.5 means w.r.t. elsticity tensor values.
I believe this is the reason you did not get any stress up, but also you need t couple with FSI the fluid to the structure. Unfortunately 3.5 is gettting to old for me, I do not have it up running anymore so I canot give ans more precis suggestions
--
Good luck
Ivar
first when you save with 3.5a, you can choose the format, m files can only be openend thereafter in a Matlab linked to COMSOL. So it's often better to save the file inthe COMSOD standard format ".mph"
THen one comment, you should avoid a Poisson modulus of 0.5 tha is not really physical, you can use 0.49 if you really want such a high value, I know some polymer or rubbers tend to have a high Poisson ratio, but take a closer look to what 0.5 means w.r.t. elsticity tensor values.
I believe this is the reason you did not get any stress up, but also you need t couple with FSI the fluid to the structure. Unfortunately 3.5 is gettting to old for me, I do not have it up running anymore so I canot give ans more precis suggestions
--
Good luck
Ivar