SimScale CAE Forum

Porous media

Hi everyone,
I was simulating muffler with absorbing filler material so for that I was used porous media option for simulation. in this porous media, I don’t know who to set below value. (unit vector1 and 2)

and I have one question, why I can’t assign cylinder in PICK VOLUME because they required a Cartesian box? correct me if I am wrong. there is one successful run without having porous media.
project link:-

Thank You.

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Hi Rohit!

Have you had a look at this post from our PowerUser @varsey: Setting Up a Simulation Using Porous Media ?

For the cartesian box you can toggle the button which is below the blue entity assignment field in your picture, there you can activate the box that you have created. Does that answer your question?



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Yes, it seems like cylinder geomentry doesnt work for setting up the porous media (for some reason). But you can set up the properties in the box, it should work the way you configured.


yes, sir, i was an applyed box but there is an error in the run. (Floating point exception.)

in this type of simulation cartesian box size matter? if the size was bigger than the outer pipe? and this porous media really work like absorbing material ? beacuse the cartesian box work like one domian and actual absorbing material just like PIPE having ID and OD (that why i was trying to use cylinder)
thank you @varsey for help. :raised_hands:


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The size of the box doesnt matter, the properties inside the box is the key. You want to set up the resistance of the media inside the pipe, so it can be a little bigger than the the pipe itself.

where i set resistance sir? in simulation setup or cad model?
and you have any idea about this error?

this error appear when the cartesian box was used in porous media.
Thank you,

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Resistance of the media is set up in the case configuration, for reference please look at the picture here:


Floating point error says that your simulation is breaking up, the reason could be in the settings or even in the mesh - please look through tour case carefully from the very beginning.

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hi sir, how to calculate this value? :point_down:

any formula ?

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Hi Rohit!

@varsey, has posted this as well in this thread: Setting Up a Simulation Using Porous Media - let us know if that helps! Also you can find this in our documentation by looking for Porous Media.




HI @varsey AND @jousefm Sir,
i was calculated the value for D and F.
in D formula dm was particles diameter for that i have 50nm value. for E (Porosity) assume in this case 80 %.
if i used above value for calculation the answer of

there is something wrong. this value was too big in this case.
please help me.
Thank you.