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linking parameters from 2 physics

Posted Aug 16, 2011, 5:58 a.m. EDT Modeling Tools & Definitions, Parameters, Variables, & Functions Version 4.2 4 Replies

David Segal
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Hi

How do I link the Lorentz force from magnetic fields to the volume force in a 2 phase laminar flow level-set physics

my model involves both these physics

thanks
Dave
4 Replies Last Post Sep 18, 2012, 2:31 p.m. EDT
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Aug 17, 2011, 4:31 a.m. EDT
Hi

depending on your model, either COMSOL has detected that there is a force value it can import and the GUI window has a pull down option to select the predefined force from the other physics, or what always works is to enter the variable name of the force from the other physics. But pls check carefully the units, one enter pressures and not absolute forces most of the time. Because a force load is a global values averaged out over the surface, while a pressure has generally a spatial distribution (this is implicit in COMSOL as the variables are mostly implicitly a function of (x,y,z)

--
Good luck
Ivar
Hi depending on your model, either COMSOL has detected that there is a force value it can import and the GUI window has a pull down option to select the predefined force from the other physics, or what always works is to enter the variable name of the force from the other physics. But pls check carefully the units, one enter pressures and not absolute forces most of the time. Because a force load is a global values averaged out over the surface, while a pressure has generally a spatial distribution (this is implicit in COMSOL as the variables are mostly implicitly a function of (x,y,z) -- Good luck Ivar
David Segal
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Posted: 1 decade ago Aug 18, 2011, 6:29 a.m. EDT


HI Ivar

Thanks , this works OK if I put the lorentz force FLtzx from the mf into the X volume force of the 2 phase fluid level set

and the same for Y and Z components

My problem now is that it does not work if I try using the 2 fluid moving mesh model instead of the level-set

the error message reads that it fails to read the variable

what am I doing wrong?

thanks

Dave

HI Ivar Thanks , this works OK if I put the lorentz force FLtzx from the mf into the X volume force of the 2 phase fluid level set and the same for Y and Z components My problem now is that it does not work if I try using the 2 fluid moving mesh model instead of the level-set the error message reads that it fails to read the variable what am I doing wrong? thanks Dave
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Aug 18, 2011, 4:15 p.m. EDT
Hi David

not sure what it could be, but have you made a brand new model, or have you just deleted and added a new physics and knitted it in ? If it's the latter case COMSOL might have changed the variable coupling names, but not updated the links.

I would at least try a Edit clear solution, + clear mesh + File Model Reset, then check and redefine all the coupling before I run a model that I adapt. That is why mostly I restart my models from scratch.

Got even caught yesterday, I re-loaded an .X_T parasolid CAD file instead of a .SLDPRT SolidWorks file, this changed my dimensions by a factor "1000" (doing an automatic conversion in my back of m to mm, actually mm to um). The results were really wrong, but it took me some time to to find the flaw, everything, including graphical views looked OK ;)

--
Good luck
Ivar
Hi David not sure what it could be, but have you made a brand new model, or have you just deleted and added a new physics and knitted it in ? If it's the latter case COMSOL might have changed the variable coupling names, but not updated the links. I would at least try a Edit clear solution, + clear mesh + File Model Reset, then check and redefine all the coupling before I run a model that I adapt. That is why mostly I restart my models from scratch. Got even caught yesterday, I re-loaded an .X_T parasolid CAD file instead of a .SLDPRT SolidWorks file, this changed my dimensions by a factor "1000" (doing an automatic conversion in my back of m to mm, actually mm to um). The results were really wrong, but it took me some time to to find the flaw, everything, including graphical views looked OK ;) -- Good luck Ivar
Hongxue Cai
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Posted: 1 decade ago Sep 18, 2012, 2:31 p.m. EDT
I want to plot in Comsol v/p, where v is velovity from a solid domain and p is pressure from an acoustic doamin. How I do it? Thanks!
I want to plot in Comsol v/p, where v is velovity from a solid domain and p is pressure from an acoustic doamin. How I do it? Thanks!

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