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Viscosity for an ideal gas

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Dear all, I have a problem in my material for a turbulant CFD problem. As a simplification, I want to model a argon gas passing through components such as an orrifice and nozzle with inlet of 0.1 lpm and pressure of 1013mbar, (which is similar to my experiment). at the end of nozzle there is a vacuum chamber with pressure of 3.5mbar. So I expect a gradient of pressure in my system from 1013mbar to 3.5 mbar (just a rough domain) and I want to use ideal gas model for my material properties to relate density to pressure.

In order to satisfy my assumption I used a density in form of {pA*0.039948/8.314/T} (borrowed from helium gas properties and changed the molar mas to molar mas of argon) and fixed dynamic viscosity of 2.2e-5. now I have 2 problems: 1. This material property is not working, every time different error appears such as "devided by zero" or "NaN or inf" or "undefined variable". 2. In the material property part I just can use absolute pressure. but I want to use and calculate density based on relative pressure.

Could you please give me some guidance to solve these problems? Thanks in advance, Best regards, Saleh


1 Reply Last Post Aug 21, 2018, 10:39 AM EDT

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Posted: 1 year ago Aug 21, 2018, 10:39 AM EDT

Dear Saleh,

I noticed that your question hasn't been answered yet. I would therefore like to advise you to send your question to support@comsol.com for a response.

Kind Regads,

Yara Soares

COMSOL BV | Röntgenlaan 37 | 2719 DX Zoetermeer Phone: +31 (0)79 363 4230 | Fax: +31 (0)79 361 4212 www.comsol.nl | yara.soares@comsol.com

Dear Saleh, I noticed that your question hasn't been answered yet. I would therefore like to advise you to send your question to support@comsol.com for a response. Kind Regads, Yara Soares ---------------------------------------------------------------------- COMSOL BV | Röntgenlaan 37 | 2719 DX Zoetermeer Phone: +31 (0)79 363 4230 | Fax: +31 (0)79 361 4212 www.comsol.nl | yara.soares@comsol.com

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