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The lateral boundary conditions types (LBC) define the way ENVI-met handles the model boundaries.
As the normal prognostic equations of the model cannot be applied to grid points on the model borders, other, more simple methods are used to obtain the needed values there.
Three different kinds of LBC can be selected in ENVI-met:
- open LBC: The values of the next grid point close to the border are copied to the border each time step.
- forced (or closed) LBC: The values of the one dimensional model are copied to the border.
- cyclic LBC: The values of the downstream model border are copied to the upstream model border.
You can choose the LBCs for temperature, humidity and for the turbulence variables. For the flow field, an open LBC will be used in any case.
You can choose the LBC types by adding the [LBC-TYPES] section to your .CF file:
00: [LBC-TYPES] ____Types of lateral boundary conditions 01: LBC for T and q (1:open, 2:forced, 3:cyclic) =1 02: LBC for TKE (1:open, 2:forced, 3:cyclic) =2
What do the lines mean?
01: LBC for T and q (Default 1=open)
LBC type for temperature and humidity. 1 is open, 2 is forced and 3 is cyclic.
02: LBC for TKE (Default 1=open)
LBC type for the turbulence variables TKE (kinetic energy) and epsilon (dissipation rate). See above.