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air flow impinge on a hot cylinder

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Old   April 28, 2014, 03:10
Default air flow impinge on a hot cylinder
  #1
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Hi,

I have a problem with a simulation. The flow configuration is as follows:

An air flow ( T = 298 K) impinge on a moving cylinder (T = 1873 K; u = 7 m/s). The boundaries around are no walls but rather open atmosphere. The aim is to detect a possible buoyancy flow because of the temperature differences. The air at the calculation area has a temperature about 323 K.

The solvers I chose are "rhoPimpleFoam" and "buoyantPimpleFoam".

First question: Are these the right solver or is there another better one?

The main problem affects the boundaries (to the atmosphere). I chose it as follows:

p:

boundary_to_atmosphere
{
type fixedValue; // OR type calculated;
value $internalField; // internalField is about 1e5

}



p_rgh:


boundary_to_atmosphere
{
type fixedFluxPressure;
value uniform 1e5;
}




T:
boundary_to_atmosphere
{
type inletOutlet;
value uniform 323;
inletValue uniform 323;
}



U:
boundary_to_atmosphere
{
type pressureInletOutletVelocity;
value uniform (0 0 0);
}




I think I did a mistake because I get a temperature lower than 273 at the internalField.

Second question: Are the boundaries correct?


Third question:
In the "thermophysicalProperties" I chose


thermoType
{
type heRhoThermo;
mixture pureMixture;
transport const;
thermo hConst;
equationOfState perfectGas;
specie specie;
energy sensibleEnthalpy;//sensibleInternalEnergy;//sensibleEnthalpy;
}


Is this correct for this type of flow?


I use OpenFoam 2.3.x


I hope somebody can help me.




Best regards,


dbnrop
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Old   April 28, 2014, 09:30
Default
  #2
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Andrew Somorjai
Join Date: May 2013
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Quote:
Originally Posted by dbnrop View Post
Hi,

I have a problem with a simulation. The flow configuration is as follows:

An air flow ( T = 298 K) impinge on a moving cylinder (T = 1873 K; u = 7 m/s). The boundaries around are no walls but rather open atmosphere. The aim is to detect a possible buoyancy flow because of the temperature differences. The air at the calculation area has a temperature about 323 K.

The solvers I chose are "rhoPimpleFoam" and "buoyantPimpleFoam".

First question: Are these the right solver or is there another better one?

The main problem affects the boundaries (to the atmosphere). I chose it as follows:

p:

boundary_to_atmosphere
{
type fixedValue; // OR type calculated;
value $internalField; // internalField is about 1e5

}



p_rgh:


boundary_to_atmosphere
{
type fixedFluxPressure;
value uniform 1e5;
}




T:
boundary_to_atmosphere
{
type inletOutlet;
value uniform 323;
inletValue uniform 323;
}



U:
boundary_to_atmosphere
{
type pressureInletOutletVelocity;
value uniform (0 0 0);
}




I think I did a mistake because I get a temperature lower than 273 at the internalField.

Second question: Are the boundaries correct?


Third question:
In the "thermophysicalProperties" I chose


thermoType
{
type heRhoThermo;
mixture pureMixture;
transport const;
thermo hConst;
equationOfState perfectGas;
specie specie;
energy sensibleEnthalpy;//sensibleInternalEnergy;//sensibleEnthalpy;
}


Is this correct for this type of flow?


I use OpenFoam 2.3.x


I hope somebody can help me.




Best regards,


dbnrop

I'm almost 100% positive buoyantPimpleFoam is the best for this. For the pressure I think you need

type calculated;

because p_rgh calculates pressure in the hotRoom example.

You would also need to setup probes (an example can be found in the TJunction tutorial in the controlDict file).

That's all I know.
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