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Old   January 26, 2012, 04:18
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Shashwat
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Dear all

I am new to CFX. I am doing the tutorial 12 flow in a catalytic converter.
I have a question in "creating porous domain"

As in the tutorial They have introduced

Basic setting > fluid and particle definition>Fluid 1>Material> Air Ideal gas

My question is

1. Why do they put "Air Ideal gas" instead of porous material honeycomb ceramic material?

Thank you

Regards
Shashwat
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Old   January 26, 2012, 06:07
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Glenn Horrocks
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The material they define is the fluid. You do not define a material for the cat converter, instead you merely define resistance coefficients.
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Old   January 27, 2012, 02:10
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Shashwat
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Dear friend

I am new to CFX. I am doing the tutorial 12 flow in a catalytic converter.
I have a question in "setting initial values" in the catalytic housing

How come they set the initial velocity -2.8m/s.? why is not zero along the Z direction?

As far as my knowledge is concerned, -ve sign indicates that the flow is in the opposite direction.

How did they calculate the initial velocity?

Please clarify

Thank you

Regards

Shashwat
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Old   January 27, 2012, 02:41
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Christoph
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Do you also read the Tutorial!? That may help

12.6.6. Setting Initial Values

A sensible guess for the initial velocity is the expected velocity through the catalyst housing. You can assume incompressible flow and apply conservation of mass to obtain an approximate velocity of 2.8 [m s^-1] through the housing based on the following known information:
The inlet velocity: 25 [m s^-1]
The cross sectional area of the inlet and housing, which can be determined using the function calculator in CFD-Post: 0.001913 m^2 and 0.024039 m^2 respectively
The porosity of the honeycomb structure: 70%
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