Reynolds number for Sphere Drag Force calculation

abhishek_kgp · October 9, 2020, 17:14

Hello Everyone!

I am simulating particle laden flow and using Particle force as sphereDrag. I was going through SphereDragForce.C file on this link:
https://www.openfoam.com/documentati...8C_source.html

I found that Re has been shown as Real component of a complex number whereas it should be Reynolds number.
Can someone please clarify how Reynolds number will be calculated?

Also I added the following lines in red to display the value of CdRe in log files but to no avail. I think sphereDrag is not getting calculated at all.
Someone please help me understand the issue if I am wrong.

if (Re > 1000.0)
{
Info << "Returned: " << .424*Re << endl;
return 0.424*Re;

}
else
{
Info << "Returned: " << 24.0*(1.0 + 1.0/6.0*pow(Re, 2.0/3.0)) << endl;
return 24.0*(1.0 + 1.0/6.0*pow(Re, 2.0/3.0));

}

Thanks in anticipation!

Regards,
Abhishek

rezaeimahdi · April 25, 2022, 09:38

Hello,

Where did you find this: "I found that Re has been shown as Real component of a complex number whereas it should be Reynolds number." ?

The Re here is the particle Re number and you can see how it calculate here:

Particle Reynolds number calculation in Lagrangian tracking?

Regarding the model to calculate drag coeff, this method is called "Liu Dynamic Drag Coefficient" that you can find in literature.

Liu, A.B., Mather, D., and Reitz, R.D. 1993. “Modeling the Effects of Drop Drag and Breakup on Fuel Sprays”, SAE Paper 930072.

Regards,

October 9, 2020, 17:14	Reynolds number for Sphere Drag Force calculation	#1
abhishek_kgp New Member Abhishek Sharma Join Date: Sep 2020 Posts: 2 Rep Power: 0	Hello Everyone! I am simulating particle laden flow and using Particle force as sphereDrag. I was going through SphereDragForce.C file on this link: https://www.openfoam.com/documentati...8C_source.html I found that Re has been shown as Real component of a complex number whereas it should be Reynolds number. Can someone please clarify how Reynolds number will be calculated? Also I added the following lines in red to display the value of CdRe in log files but to no avail. I think sphereDrag is not getting calculated at all. Someone please help me understand the issue if I am wrong. if (Re > 1000.0) { Info << "Returned: " << .424Re << endl; return 0.424Re; } else { Info << "Returned: " << 24.0(1.0 + 1.0/6.0pow(Re, 2.0/3.0)) << endl; return 24.0(1.0 + 1.0/6.0pow(Re, 2.0/3.0)); } Thanks in anticipation! Regards, Abhishek

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April 25, 2022, 09:38		#2
rezaeimahdi Member mahdi Join Date: Nov 2015 Location: Paris, France Posts: 32 Rep Power: 10	Hello, Where did you find this: "I found that Re has been shown as Real component of a complex number whereas it should be Reynolds number." ? The Re here is the particle Re number and you can see how it calculate here: Particle Reynolds number calculation in Lagrangian tracking? Regarding the model to calculate drag coeff, this method is called "*Liu Dynamic Drag Coefficient*" that you can find in literature. Liu, A.B., Mather, D., and Reitz, R.D. 1993. “Modeling the Effects of Drop Drag and Breakup on Fuel Sprays”, SAE Paper 930072. Regards,