Changes between Version 15 and Version 16 of doc/tec/bc

Timestamp:

Apr 26, 2016 7:50:25 PM (9 years ago)

Author:

Giersch

Comment:

--

doc/tec/bc

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 = Boundary conditions =
 
+PALM offers a variety of boundary conditions. Dirichlet or Neumann boundary conditions can be chosen for ''u'', ''v'', ''θ'',
+''q'',,v,,, and ''p''^∗^ at the bottom and top of the model. For the horizontal velocity components the choice of Neumann (Dirichlet) boundary conditions yields free-slip (no-slip) conditions. Neumann boundary conditions are also used for the SGS-TKE. Kinematic fluxes of heat and moisture can be prescribed at the surface instead (Neumann conditions) of temperature and humidity (Dirichlet conditions). At the top of the model, Dirichlet boundary conditions can be used with given values of the geostrophic wind. By default, the lowest grid level (''k = 0'') for the scalar quantities and horizontal velocity components is not staggered vertically and defined at the surface (''z = 0''). In case of free-slip boundary conditions at the bottom of the model, the lowest grid level is defined below the surface (''z = - 0.5 
+Δz'') instead. Vertical velocity is assumed to be zero at the surface and top boundaries, which implies using Neumann conditions for pressure.
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 == Constant flux layer ==
-
 === Basics ===
+
 Following Monin-Obukhov similarity theory (MOST) a constant flux layer can be assumed as boundary condition between the surface and the first grid level where scalars and horizontal velocities are defined (''k'' = 1, ''z'',,MO,, = 0.5 ''Δz''). It is then required to provide the roughness lengths for momentum ''z'',,0,, and heat ''z'',,0,h,,. Momentum and heat fluxes as well as the horizontal velocity components are calculated using the following framework. The formulation is theoretically only valid for horizontally-averaged quantities. In PALM we assume that MOST can be also applied locally and we therefore calculate local fluxes, velocities, and scaling parameters.
 
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 = References =
-* [=#holtslag] '''Holtslag, AAM and Bruin HARD.''' 1988. Applied modelling of the night-time surface energy balance over land. J. Appl. Meteorol., 27, 689–704.
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-* [=#panofsky] '''Panofsky, HA and Dutton, JA.''' 1984. Atmospheric Turbulence, Models and Methods for Engineering Applications, John Wiley & Sons, New York.
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-* [=#paulson] '''Paulson, CA''' 1970. The mathematical representation of wind speed and temperature profiles in the unstable atmospheric surface layer. J. Appl. Meteorol., 9, 857–861.
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+* [=#holtslag] '''Holtslag AAM, Bruin HARD.''' 1988. Applied modelling of the night-time surface energy balance over land. J. Appl. Meteorol., 27, 689–704.
+
+* [=#panofsky] '''Panofsky HA, Dutton JA.''' 1984. Atmospheric Turbulence, Models and Methods for Engineering Applications, John Wiley & Sons, New York.
+
+* [=#paulson] '''Paulson CA''' 1970. The mathematical representation of wind speed and temperature profiles in the unstable atmospheric surface layer. J. Appl. Meteorol., 9, 857–861.
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