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How to implement massless formulation in particle tracing

Posted Feb 22, 2012, 10:14 p.m. EST Charged Particle Tracing, Particle Tracing for Fluid Flow Version 4.3a 8 Replies

John R Puentes
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Does anybody know how to implement mass-less formulation in the particle tracing module instead of drag force?

What is the boundary condition in this case?

Thanks
8 Replies Last Post Nov 15, 2013, 11:44 p.m. EST
Nagi Elabbasi Facebook Reality Labs
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Posted: 1 decade ago Feb 22, 2012, 10:34 p.m. EST
Set Formulation = Massless in the Formulation section of the settings under the Particle Tracing node.
Set Formulation = Massless in the Formulation section of the settings under the Particle Tracing node.
John R Puentes
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Posted: 1 decade ago Feb 22, 2012, 11:06 p.m. EST
Thank you.

Regarding the boundary condition , for drag force an additional drag force boundary condition is needed. What about boundary condition for mass-less?

Thanks
Thank you. Regarding the boundary condition , for drag force an additional drag force boundary condition is needed. What about boundary condition for mass-less? Thanks
John R Puentes
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Posted: 1 decade ago Feb 22, 2012, 11:08 p.m. EST
Thank you
Thank you
ComsolRaff
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Posted: 1 decade ago Nov 15, 2013, 10:05 a.m. EST
Dear all,

I'm trying to use particle tracing in a static mixer to simulate a mixing between 2 gases.
When I set Newtonian as formulation and bounce as wall condition I correctly find the particle trajectories at the outlet (Particle tracing bounce.png attached).

In every way to use this formulation i have to set particles diameter and density, but in my case i don't have solid particles in the flow.
I think that should be more correct to use the massless formulation.
However when i try to do it the particles don't leave the inlet section as they have no velocity (Particle tracing massless.png attached).

What is wrong with my model?

Thank you in advance for your support.

Raffaella
Dear all, I'm trying to use particle tracing in a static mixer to simulate a mixing between 2 gases. When I set Newtonian as formulation and bounce as wall condition I correctly find the particle trajectories at the outlet (Particle tracing bounce.png attached). In every way to use this formulation i have to set particles diameter and density, but in my case i don't have solid particles in the flow. I think that should be more correct to use the massless formulation. However when i try to do it the particles don't leave the inlet section as they have no velocity (Particle tracing massless.png attached). What is wrong with my model? Thank you in advance for your support. Raffaella
ComsolRaff
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Posted: 1 decade ago Nov 15, 2013, 10:05 a.m. EST
Dear all,

I'm trying to use particle tracing in a static mixer to simulate a mixing between 2 gases.
When I set Newtonian as formulation and bounce as wall condition I correctly find the particle trajectories at the outlet (Particle tracing bounce.png attached).

In every way to use this formulation i have to set particles diameter and density, but in my case i don't have solid particles in the flow.
I think that should be more correct to use the massless formulation.
However when i try to do it the particles don't leave the inlet section as they have no velocity (Particle tracing massless.png attached).

What is wrong with my model?

Thank you in advance for your support.

Raffaella
Dear all, I'm trying to use particle tracing in a static mixer to simulate a mixing between 2 gases. When I set Newtonian as formulation and bounce as wall condition I correctly find the particle trajectories at the outlet (Particle tracing bounce.png attached). In every way to use this formulation i have to set particles diameter and density, but in my case i don't have solid particles in the flow. I think that should be more correct to use the massless formulation. However when i try to do it the particles don't leave the inlet section as they have no velocity (Particle tracing massless.png attached). What is wrong with my model? Thank you in advance for your support. Raffaella
Nagi Elabbasi Facebook Reality Labs
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Posted: 1 decade ago Nov 15, 2013, 10:17 a.m. EST
Dear Raffaella,

The Particle Velocity is probably set to the default 0 values under the Particle Properties node. Set the velocity to u, v, w or whatever variable names you are using for the fluid-flow.

Nagi Elabbasi
Veryst Engineering
Dear Raffaella, The Particle Velocity is probably set to the default 0 values under the Particle Properties node. Set the velocity to u, v, w or whatever variable names you are using for the fluid-flow. Nagi Elabbasi Veryst Engineering
ComsolRaff
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Posted: 1 decade ago Nov 15, 2013, 11:23 a.m. EST
Hi Nagi,
thank you for your reply. As you suggested the velocity was set to zero.
Using the velocity components the particles leave the inlet section but they stop as they arrive on the first element because the wall condition is set to freeze. (Image attached)

In the massless formulation i can not set the bounce condition.

Which kind of post processing do you suggest to highlight the particle paths from the inlet towards the outlet?

Thank you for the support.

Raffaella


Dear Raffaella,

The Particle Velocity is probably set to the default 0 values under the Particle Properties node. Set the velocity to u, v, w or whatever variable names you are using for the fluid-flow.

Nagi Elabbasi
Veryst Engineering


Hi Nagi, thank you for your reply. As you suggested the velocity was set to zero. Using the velocity components the particles leave the inlet section but they stop as they arrive on the first element because the wall condition is set to freeze. (Image attached) In the massless formulation i can not set the bounce condition. Which kind of post processing do you suggest to highlight the particle paths from the inlet towards the outlet? Thank you for the support. Raffaella [QUOTE] Dear Raffaella, The Particle Velocity is probably set to the default 0 values under the Particle Properties node. Set the velocity to u, v, w or whatever variable names you are using for the fluid-flow. Nagi Elabbasi Veryst Engineering [/QUOTE]

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Nagi Elabbasi Facebook Reality Labs
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Posted: 1 decade ago Nov 15, 2013, 11:44 p.m. EST
Hi Raffaella,

What you probably need is a much smaller time step size for the particle tracing solver, not a bounce condition.

Nagi Elabbasi
Veryst Engineering
Hi Raffaella, What you probably need is a much smaller time step size for the particle tracing solver, not a bounce condition. Nagi Elabbasi Veryst Engineering

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