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porous media - C1 C2 values for cylinders

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Old   October 15, 2004, 15:08
Default porous media - C1 C2 values for cylinders
  #1
Ralf Schmidt
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Hi!

I have a problem defining the Hi!

I want to simulate the air flow (5m3/s) through a chamber (1m x1m cross section) with a group of cylinder placed in parallel to the flow (40 mm diameter and 200 mm length).

There are many possible configurations of the cylinder positions. They might be placed in up to 3 levels on top of each other with or without a shift. Also number of cylinders may vary in a range of 10 to 600.

example for possible cylinder configurations:

I I I I I I I I

I I I I I I I I I

To avoid simulating every possible situation, I want to use the porous zone model. But I have difficulties finding the appropriate parameters for C1 and C2. When using the ergun equation suggested by the fluent manual, the Re number is to large.

What happened in-between the cylinders is not important - for the first attempt. The Air flow above and below is interesting.

Do you have any idea??? Thanks in advance!

Ralf
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Old   October 17, 2004, 18:12
Default the cylinder configurations
  #2
Ralf Schmidt
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Hi, the cylinder configurations are:

I_I_I

_I_I_

I_I_I

or

I_I_I

I_I_I

I_I_I
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Old   October 26, 2004, 05:23
Default Re: the cylinder configurations
  #3
Hannibal
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Hallo Ralf, Was willst berechnen??? Den Druckverlust? Ist der entscheindend für dein Problem?? vielleicht ist denn möglich mehr zu sagen! Gruß
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Old   October 27, 2004, 06:40
Default pressure drop and flow distribution
  #4
Ralf Schmidt
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Pressure drop is important but also the flow distribution on the borders of the porous medium (inlet and outlet velocity, mass flow,…). Later, the cylinders will have elevated temperature and the heat transfer to the cold gas inside the porous medium should equal the one from the cylinders.

Der Druckverlust der porösen Zone ist wichtig, aber auch die Verteilung der Strömung um die Zone herum (ein- und auslass Geschwindigkeit, Massenstrom,...) Später sollen die Zylinder erhitzt werden und der Wärmeübergang der Zylinder an das kalte Gas soll mit dem im porösen Medium übereinstimmen.
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Old   October 27, 2004, 09:55
Default Re: pressure drop and flow distribution
  #5
Hannibal
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Hallo nochmal, In deinem fall kannst du C1 und C2 etweder aus einem analytischen Betrachtung oder aus expliziten Berechnungen der aufgelösten Geometrie bestimmen, in dem du den Druckverlust gleich setzt. Ähnliches Problem mit dem Wärmeübergang (Nusseltzahl) wirst du überigens haben!!! (Bei der Aufgabenstellung weiss ich nicht ob es sinnvoll ist ein (isotopes)Porousmediamodell zu nehmen Gruß!
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Old   October 27, 2004, 13:35
Default Re: pressure drop and flow distribution
  #6
Ralf Schmidt
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Is there a (simple) possibility, to calculate the resistance of a (large) number of cylinders, placed behind or above each other or in mixed configuration? To simulate each cylinder configuration separately should be avoided in order to minimize computing time and model complexity.

The porous model in Fluent gives the possibility to set anisotropic C1 and C2 values

--------------

Gibt es eine (einfache) Möglichkeit, den Widerstand einer Vielzahl von hintereinander, übereinander und durcheinander stehenden Zylindern analytisch zu berechnen? Die explizite Betrachtung der Geometrie soll gerade vermieden werden, um das Simulationsmodell zu vereinfachen.

Das Porositätsmodell in Fluent erlaubt, anisotrope Werte für C1 und C2 zu setzen.

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Old   November 18, 2004, 07:35
Default Re: pressure drop and flow distribution
  #7
Cvete Dimitrieska
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I have problem with flow and pressure distribution between two parrallel plates. Let me fill free to ask you for help, if you can send me theoretical mathematical model or softver for solving this problem. Thank's
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