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Using values from the "Equation view" section as input in a Coupled Multi physics model
Posted Dec 2, 2015, 10:51 p.m. EST Acoustics & Vibrations, Microfluidics, Simulation Apps, Geometry, Modeling Tools & Definitions, Parameters, Variables, & Functions, Results & Visualization, Studies & Solvers, Structural Mechanics Version 4.3 2 Replies
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I am doing a Multiphysics modelling on the formation of an ultrasonic standing wave field that is used to separate suspended particles in a continuous medium (a colloid).
As you can see from the attached files (One Comsol file and one journal article), I am trying to imitate the model that is given in the journal article but I am viewing the model on top of it, instead of looking at its side.
In the model, I have created three domains to model a piezeoelectric transducer acting on a fluid domain surrounded by PMMA wall, the same as the one in the journal article.
The problem here is that once I used mod1.acpr.p_t (total acoustic pressure) for the boundary load acting on the PMMA wall and mod1.utt and mod1.vtt (acceleration field of solid mechanics) for the acceleration boundary on the fluid domain, an error came up stating that they failed to evaluate the variable, the expression and the operator for acpr.p_t and utt or vtt. How do I solve this problem?
My supervisor told me the reason I couldn't use acpr.p_t and utt and vtt were because the model is not coupled yet. If this is the case, how do I make sure I couple everything in the model?
Fyi, the result went well without errors once I define a value for the boundary load and the acceleration boundary instead of using acpr.p_t and utt or vtt but I must use acpr.p_t and utt or vtt because that is what the author(s) did for the journal article.
I appreciate if anyone can help me, thank you in advance :)
Regards,
Badri
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Use form union instead of form assembly in your geometry sequence. Then the Pressure Acoustics boundary will be the same as the Solid Mechanics boundary and the variables can be used to couple the interfaces.
In your example, you could use the predefined announced variables instead of typing the variable names manually. On the Boundary Load, change User defined to Acoustic load per unit area (acpr/pam1). On the Normal Acceleration, set the Type to Acceleration and change User defined to Acceleration (solid/lemm1).
Another option in 4.3 is to use the Acoustic-Piezoelectric Interaction, Frequency Domain multiphysics interface to set up the model. Then the coupling is predefined.
In 5.2, you add the Acoustic-Structure Boundary multiphysics coupling to get the predefined coupling.
Best regards,
Elin Svensson
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It worked, but the problem here now is that I got zero results. I don't know the problem here, what am I missing?
If I define a value I get good results, but after using the variables or predefined announced variables, I got zero results. Hmm...
I did this model on 31st October but I don't think I can solve this without anyone's help.
I've never used variables as inputs back when I was doing my assignments, but now the situation is different.
Regards,
Badri
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