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Fluid flow in a 2D collapsible tube
Posted Mar 9, 2011, 8:30 p.m. EST Fluid & Heat, Geometry, Mesh, Structural Mechanics Version 4.1 1 Reply
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Dear Sir/Madam,
I am really a new beginner for Comsol 4.1, and it really drive me to die!
My project is about simulating the 2D steady flow in a collapsible tube which envolves the Navier-Stokes Equation for incompressible Newtonian Fluid; Structure Mechanics and ALE moving mesh!
I try to did what a gentelmen( who is really so nice) said, I am so sorry I still feel so confused! can someone give me more suggestions!
1.the Geometry
I add the membrane part. Is it still a slab? can you check it for me? Because if the geometry is not right, next work would be sucks!
2. I try to do the physics 'laminar flow' first. As to what he said
"To get a fluid flow to run quickly in a model, you shoudl add some initial conditions on the velocity (an approximate v^2 profile across the tube section is OK, then add some pressure drop (i.e. simple analytical Poiseille value is OK) This will strongly improve your convergence."
I do not know how to do this. Is it in 'Initial Value'---Velocity Field'---when I type V^2 in the X window, it turns to be orange color.
3. In the solid mechanics physics, my equation would be
P-Pe(external pressure)+2*H*T(tension)=0
2*H=dh^2/dx^2/(1+dh^2/dx^2)^(3/2) curvature equation
But in the model the equation is
rho*du^2/dt^2-delt stress=Fv
How can I write this into the model?
Thank you so much. I am so appreciate if someone can help me, even a little!
Thank you !
I am really a new beginner for Comsol 4.1, and it really drive me to die!
My project is about simulating the 2D steady flow in a collapsible tube which envolves the Navier-Stokes Equation for incompressible Newtonian Fluid; Structure Mechanics and ALE moving mesh!
I try to did what a gentelmen( who is really so nice) said, I am so sorry I still feel so confused! can someone give me more suggestions!
1.the Geometry
I add the membrane part. Is it still a slab? can you check it for me? Because if the geometry is not right, next work would be sucks!
2. I try to do the physics 'laminar flow' first. As to what he said
"To get a fluid flow to run quickly in a model, you shoudl add some initial conditions on the velocity (an approximate v^2 profile across the tube section is OK, then add some pressure drop (i.e. simple analytical Poiseille value is OK) This will strongly improve your convergence."
I do not know how to do this. Is it in 'Initial Value'---Velocity Field'---when I type V^2 in the X window, it turns to be orange color.
3. In the solid mechanics physics, my equation would be
P-Pe(external pressure)+2*H*T(tension)=0
2*H=dh^2/dx^2/(1+dh^2/dx^2)^(3/2) curvature equation
But in the model the equation is
rho*du^2/dt^2-delt stress=Fv
How can I write this into the model?
Thank you so much. I am so appreciate if someone can help me, even a little!
Thank you !
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1 Reply Last Post Mar 14, 2011, 3:00 a.m. EDT
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Posted:
1 decade ago
Hi
for the initial conditions (telling the model that the fluid is flowing from the "initial" step
see also
www.comsol.eu/community/forums/general/thread/12974/
there are several treads and a few examples, search the forum, and aways check the KB (Knowledge Base) on the main site
another point, here in 2D you are simulating a slab (1[m] long in Z into the paper direction) collapsing plate and not really a tube
I have added a simple model built upon your geometry, the material properties of the wall are just free number, to be changed to something more natural. YOu can see how I start the velocity and the pressure just to help the solver. One can also see the pressure drop and the effect on the tube. There are now many ways to improve this. It's a 4.1.0.85 model and you need the "solid" and "spf" laminar flow physics
One thing, more WARNING: this model is not complete, as the change of pressure is changing the solid shape, but the change of the solid IS NOT changing the tube section for the fluid, this coupling must still be implemented ! And you should use the FSI physics, pre-cooked and ready ;)
Re-note: one never checks enough, my Poiseuille formula is not taking into account the pressure drop along the tube so I'm missing a *(1-(x/0.014[m])) in there. Anyhow with the low velocity the solver seems happy with any low pressure value
For a better visualisation turn on the "2D Plot Group 1" in the Study Solver Configuration Stationary Solver 1 Fully Coupled - Results while solving
--
Good luck
Ivar
for the initial conditions (telling the model that the fluid is flowing from the "initial" step
see also
www.comsol.eu/community/forums/general/thread/12974/
there are several treads and a few examples, search the forum, and aways check the KB (Knowledge Base) on the main site
another point, here in 2D you are simulating a slab (1[m] long in Z into the paper direction) collapsing plate and not really a tube
I have added a simple model built upon your geometry, the material properties of the wall are just free number, to be changed to something more natural. YOu can see how I start the velocity and the pressure just to help the solver. One can also see the pressure drop and the effect on the tube. There are now many ways to improve this. It's a 4.1.0.85 model and you need the "solid" and "spf" laminar flow physics
One thing, more WARNING: this model is not complete, as the change of pressure is changing the solid shape, but the change of the solid IS NOT changing the tube section for the fluid, this coupling must still be implemented ! And you should use the FSI physics, pre-cooked and ready ;)
Re-note: one never checks enough, my Poiseuille formula is not taking into account the pressure drop along the tube so I'm missing a *(1-(x/0.014[m])) in there. Anyhow with the low velocity the solver seems happy with any low pressure value
For a better visualisation turn on the "2D Plot Group 1" in the Study Solver Configuration Stationary Solver 1 Fully Coupled - Results while solving
--
Good luck
Ivar
Attachments: