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Description: Windfield - temperature | Version: 4.9.0 | Updated: 10.03.09 | |
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By activating the temperature in the graphical user interface the temperature equation is solved in PHOENICS. The influence of the temperature on the windfield is considered by the Boussinesq approximation in the the momentum equations. An additional source term depending on the temperature stratification is considered in the equation for turbulent kinetic energy and dissipation. For applying the Boussinesq approximation a reference temperature must be given. This reference temperature is specified depending on the way of initialization.
In WindSim there are three different possibilities to initialize the temperature and to consider stability effects in the simulations.
1) Initializing from Monin-Obuhkov length: This method can be used if no nesting procedure is applied. The inlet profiles are changed according to the stability of the atmosphere and the temperature equation is solved so that blocking effects due to stable conditions can be simulated. A linear temperature gradient is calculated depending on the stability of the atmosphere and taken as reference temperature and for the initialisation of the temperature.
2) Initializing from temperature gradient: The profiles at the inlet of the simulation domain are calculated as log profiles (neutral atmosphere) as in the default WindSim simulation without temperature. With this setting the developement of the stability dependend wind profiles from the neutral profiles can be investigated. The specified temperature gradient is taken as reference temperature and for the initialisation of the temperature.
3) Initialising from mesoscale: The profiles at the inlet of the simulation domain are interpolated from the mesoscale meteorological data. The temperature of the mesoscale model is taken as reference temperature and for the initialisation of the temperature. This is the most convienent way for applying the temperature equation as all temperature information is available and no simplifications need to be made.
As WindSim is only able to simulate steady state the model is not yet able to simulate strong unstable atmospheric conditions as this will never lead to a steady state or a well converged solution. Adding the temperature equation sometimes makes the convergence more difficult; a switch to another solver or the convergence wizard may help.