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Velocity reinitialization in particle tracing module

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Hi everyone,

I am trying to model a 2D particle particle collision using velocity reinitialization.
What I want is, the velocity should reinitialization into a set of specified x and y velocity components, whenever the r < 0.03. This is what I tried:

1. I have defined distance between particles using dest function. r= sqrt(qx-dest(qx)^2+(qy-dest(qy)^2+0.02)

2. Then I defined an analytic function as step1(-r) with argument r. (step function is already been defined under comp1 with location 0.03)

3. Then I put e = an1(r)

But I am getting an error message as "Internal error in expression evaluation.
- Undefined operator.: dest
- Feature: Time-Dependent Solver 1 (sol1/t1)"

When i put an arbitrary function of x and y instead of an1(r), it worked. It seems dest function can't be an entry for e. But I am not sure.
Pls help me....
Any other ways to do 2D collision is also greatly appreciated.

Thanks in advance :))))

2 Replies Last Post Jul 13, 2015, 7:54 a.m. EDT
Gunnar Andersson COMSOL Employee

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Posted: 9 years ago Jul 13, 2015, 6:59 a.m. EDT
It seems dest function can't be an entry for e. But I am not sure.


Functions can only depend on other functions and parameters defined in Global Definitions > Parameters. I think that you can achieve what you want using a variable definition instead of a function.

[QUOTE]It seems dest function can't be an entry for e. But I am not sure.[/QUOTE] Functions can only depend on other functions and parameters defined in Global Definitions > Parameters. I think that you can achieve what you want using a variable definition instead of a function.

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Posted: 9 years ago Jul 13, 2015, 7:54 a.m. EDT

It seems dest function can't be an entry for e. But I am not sure.


Functions can only depend on other functions and parameters defined in Global Definitions > Parameters


Hi

So functions can't depend on variables? Can a function be an entry of "e" ?
I want e to be 0 for r (which is a variable depending on particle degree of freedom qx and qy) > 0.03 and otherwise e can be any value other than 0. If e can take a variable k (lets say ), then this k should depend on r (since e should react with change in r ). Could you tell me how we can implement this in comsol?

[QUOTE] [QUOTE]It seems dest function can't be an entry for e. But I am not sure.[/QUOTE] Functions can only depend on other functions and parameters defined in Global Definitions > Parameters [/QUOTE] Hi So functions can't depend on variables? Can a function be an entry of "e" ? I want e to be 0 for r (which is a variable depending on particle degree of freedom qx and qy) > 0.03 and otherwise e can be any value other than 0. If e can take a variable k (lets say ), then this k should depend on r (since e should react with change in r ). Could you tell me how we can implement this in comsol?

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