Hi,

I'm trying to create a new user- defined material for my simulation. For this, in the materials panel, I clicked on User- defined material and entered the density and viscosity of the materials that I'm using as these are the only properties that I'm interested in. Should I retain the other values (i.e. specific heat, thermal conductivity, etc as default (that of air))?

then I hit the Change/ Create button? In the Report reference values panel, I changed the default values of density, and viscosity to my values and asked to compute from from the inlet zone.

Is this the right way to create a new user- defined material? Would this be any cause for the simulation to blow up? I'm facing convergence trouble in my simulatuion and am wondering if the material properties has anything to do with it? theresiduals just keep on increasing to the order of 10e+12 and higher and show no sign of decreasing...... they just stay put at that high value.

Thanks

I feel that the interface of creating materials in Fluent is quite stupid. I do know know why they did not make something called "creat new" and "Change" separately. I make confused with this and take a couples of time to find out how to do this. First, you should choose any material which remain in Material. For example, you choose the "air" and then change the name of material you want to create, for example "gas mixture", then you click "change/create". They will ask "Change/create gas mixture and overwrite the air?". You should choose No. After that, you can see Gas mixture in Fluent Fluid Materials but it still retains old values of the Air. You change these values as you defined in Gas Mixture. Finally, click "Change/Create" again. Then you are successful to make a new material which you want.

Hi,

I didn't quite understand what you said- when I HIT THE change/ create button tyhe first time (with air as the default fluid), nothing happened. Then I hit the User- defined materials and hit the NEW button. Then entered the density and viscosity of my material, saved it and then hit the Change/ create button. I was never asked the question whether to overwrite air. Then I closed the panel.

Then in the report reference values panel, I again changed the density and viscosity from the default values to my values. Then asked to compute from the inlet zone.

That's all I did. Is it right?

Thanks.

OK. First time, you choose any type of materials, for example AIR. You delete the name of AIR, and rename this name by the other name of material you want (for example "Gas mixture"). And then, when you hit the Change/Create button, it will display the message "... overwrite Air?". And then you click NO. You will see in Fluent Flow Material that there are two materials: one is Air and the other is Gas mixture. Click Gas mixture and change all values such as Density, Viscosity ... as you defined for Gas Mixture. When conplete it, click Change/Create button. That is all.

You did not get any message because you kept the material of AIR originaly and did not rename it.

[hem233]

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