RANS eddy viscosity

FITNAH-3D

Christian Wetzel's picture
Submitted by Christian Wetzel on June 11, 2018 - 11:38am
Main hypothesis

FITNAH (Flow over Irregular Terrain with Natural and Anthropogenic Heat sources) has been developed mainly at the Leibniz Universität Hannover, Germany as a mesoscale model. It is applied in the area of wind energy, urban climate and environmental meteorology. For about twenty years FITNAH is used for wind energy site assessment and wind potential mapping by GEO-NET Umweltconsulting GmbH.

CFDWind2.0

Submitted by Roberto A. Chav... on May 27, 2015 - 12:00am
Main hypothesis

Similar to CFDWind1, this model assumes isotropic eddy-viscosity turbulence,and the two-equation closure scheme (k-ε) modified for atmospheric flows. However, in order to extend the surface layer limitations to the full Atmospheric Boundary Layer (ABL) depth, it is necessary to include Coriolis effects and to limit the growth of turbulence with height, as demonstrated by Detering & Etling (1985).

This is achieved in the k-ε by adopting the Apsley & Castro (1994) correction on the Cε1 constant for neutral conditions.

A simulation of horizontally homogeneous conditions (i.e. a 1D ) is firstly carried out as a precursor simulation in order to define the inlet conditions for the real-terrain run.

CFDWind1.1

Submitted by Roberto A. Chav... on May 27, 2015 - 12:00am
Main hypothesis

This model is formulated with the assumptions of isotropic eddy-viscosity turbulence and the k-ε two-equation closure scheme modified for atmospheric flows.

CFDWind1 deals with surface boundary layer (SBL) by imposing a set of coefficients as well as proper modifications to the boundary conditions (inlet boundary and wall functions) in order to comply with the Monin-Obukhov Similarity Theory (MOST) as proposed by Richards & Hoxey (1993) and Parente et al. (2011). 

CFDWind 1.0

Submitted by Roberto A. Chav... on May 16, 2015 - 12:00am
Main hypothesis

Steady-state, surface layer, isotropic eddy-viscosity turbulence, boussinesq approximation for air density.

In this first version of CFDWind1, the near wall inconsistency was solved by using the Blocken et al. 2007 approach which was inherited from the previous implementation in the commercial solver Fluent, which does not allow to access the source code in order to modify the wall functions.   Further versions (CFDWind1.1 and CFDWind2) have updated this condition to the more consistent formulation of Richards & Hoxey.

flapFOAM RANS

Submitted by Jonas Schmidt on May 5, 2015 - 10:53am
Main hypothesis

12 RANS simulations of a uniform non-rotating actuator disk were carried out using OpenFOAM version 2.1.1, with k-e turbulence model including additional dissipation near the rotor, a la El-Kasmi and Masson 2008. These 12 simulations form a data base, from which the wake deficit data is interpolated at arbitrary inflow velocities at hub height. This way CFD simulations are used to define a numerical wake model. flapFOAM is a new wind farm modelling software that is currently in development at Fraunhofer IWES.

Windmodeller (Ansys-CFX)

Benjamin Martinez's picture
Submitted by Benjamin Martinez on May 5, 2015 - 10:49am
Main hypothesis

- Steady-state RANS for neutral simulations

- Accounts for atmospheric stability by adding an additional energy conversation equation formulated in terms of the potential temperature and using the k-epsilon closure scheme. Surface conditions are determined via heat flux or temperature gradient.

- Actuator Disk Modelling for Wakes