http://oa.upm.es/20830/1/INVE_MEM_2011_144134.pdf
In this paper, in boundary condition, it has been mentioned,
The outlet boundary is defined as pressure outlet, the lateral boundary as zero gradient or symmetry, and
the top boundary is defined by fixing the inlet values of wind speed, turbulent kinetic energy and turbulent dissipation rate
at the top height and by assuming a constant friction velocity.
Also is it ok define the roughness constant to be greater than 1 via UDF?
Dear sir
you can read the thesis
https://fenix.tecnico.ulisboa.pt/downloadFile/563345090413764/Thesis_RehmanDanish.pdf
The boundary conditions are specified to be consistent with Richards and Hoxey approach. Check this work: https://www.researchgate.net/publication/257011546_RANS_simulation_of_ABL_flow_over_complex_terrains_applying_an_Enhanced_k-e_model_and_wall_function_formulation_Implementation_and_comparison_for_fluent_and_OpenFOAM
Article RANS simulation of ABL flow over complex terrains applying a...
Dear Ijaz,
You could use a moving-wall boundary condition for the top of your domain. As you said, at the top you specify the wind speed, TKE and TDR that are consistent with the values from the inlet at the corresponding height. If you use this type of boundary condition, you should make sure that the domain is tall enough so that the confinement of the flow does not affect your solution. For this purpose you can repeat your simulation with a taller domain and check if there is any change on the variables you are interested in.
I hope this helps!
@Anand it is tubulent kinetic energy (k) and turbulent dissipitation rate (epsilon)
@Ali thanks, I have gone through it, I will check the proposed way by applying shear stress based on friction velocity
@Harish thanks, actually this paper mentions about inlet condition, on applying so some times velocity at the free space above certain height of the turbine, can't be maintained
@Benjamin Thank you for suggestion
Actually what I did, Is I made the top as velocity inlet and specified the component of the velocity parallel not normal (as we mention in usual cases) and specified TKE and TDR values based on ABL formtula at tha height and roughness length, by doing so velocity and turbulent properies are maintained at the height, since the flow is parallel to original inlet flow, it is not affecting the stream lines or velocity inlet. Also aid in quicker convergence.
- Badges
- Science topic