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 shaswat January 26, 2012 05:18

Help needed

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

 ghorrocks January 26, 2012 07:07

The material they define is the fluid. You do not define a material for the cat converter, instead you merely define resistance coefficients.

 shaswat January 27, 2012 03:10

help needed

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?

Thank you

Regards

Shashwat

 energy382 January 27, 2012 03:41

Do you also read the Tutorial!? That may help :D

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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