[Noob]

Hello Everybody,

I am new to OpenFoam and have the task to simulate in OpenFoam a turbulent round jet. I generated the mesh as a axisymmetry blockMesh with a nozzle and a open domain for the free flow. The nozzle outlet diameter is 10 mm and I want to get high Reynolds number at the outlet to compare the values with table 2 (https://www.diva-portal.org/smash/ge...FULLTEXT01.pdf)

Actually I am not sure how to specify the boundary conditions and initial conditions for the open domain. As basis I suggested to use the FOAMTUTORIAL flowWithOpenBoundary. I specified every patch of the domain which is beeing the outlet like the atmosphere from the tutorials.

That means:
k /Omega -> inletOutlet;
inletValue uniform $Inlet;
value uniform $Inlet;

nut -> calculated; uniform 0;

p ->totalPressure;

p0 uniform 0;
value uniform 0;

U-> pressureInletOutletVelocity;
value uniform (0 0 0);


I don't understand which value I should use for the k and omega. For the simulation I specified fixedValues for the nozzle outlet to get a turbulent flow but this couldn't be the same values. Which value do I need for a atmosphere?

I hope you could help me with my problem.

Kind regards,
Noob

[bjnieuwboer]

This website shows how to relate your turbulent quantities to the velocity: https://www.cfd-online.com/Wiki/Turb...ary_conditions

For turbulent inlets (in RANS modelling) you can use 'turbulentIntensityKineticEnergyInlet' for your turbulent kinetic energy. It computes this based on the equations provided in the website. https://www.openfoam.com/documentati...alarField.html)

Similarly, you can use 'turbulentMixingLengthFrequencyInlet' for the dissipation rate omega. (https://www.openfoam.com/documentati...frequency.html)

For the atmosphere, I would use inletOutlet