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BL_INIT - Boundary layer initialization

Structured Grids

BL_INIT nb ixs str igrs [delt] nbli nzone

For ideal gases (i.e., no CHEMISTRY) and structured grids, the BL_INIT keyword may be used to initialize a j or k boundary with a laminar or turbulent flat plate boundary layer. Providing a better initial guess in these tightly clustered (and time step limiting) near-wall regions can yield faster convergence. Historically, this option was used on slower computer systems, but is rarely used today. The user-specified values are defined as:

    nb   A number from 1 to 4 indicating which boundary to initialize

    1  for j = 1
2  for j = jmax
3  for k = 1
4  for k = kmax

ixs Integer indicating method for specifying the axial location to start the boundary layer:

    1  to specify the i index
2  to specify the x station

str i index or x location to start the boundary layer, depending on the value of ixs
igrs Integer indicating method for specifying the initial height of the boundary layer:

    1  to specify the number of grid points from the wall
2  to specify the thickness
3  to compute thickness from initial x station

delt Number of grid points in boundary layer (if igrs = 1), or boundary layer thickness (inches) (if igrs = 2)
nbli Integer indicating type of boundary layer and whether to keep constant thickness or grow with x

    1  Turbulent profile, growing with x
−1  Turbulent profile, constant thickness
2  Laminar profile, growing with x
−2  Laminar profile, constant thickness

nzone Zone number for initialization

    0  All zones
> 0  Zone nzone only

A flat plate temperature distribution will also be constructed consistent with the wall temperature boundary condition of either adiabatic or constant temperature wall, as specified using the WALL TEMPERATURE keyword. However, this keyword cannot be used with WALL TEMPERATURE EQUILIBRIUM.

Note: BL_INIT cannot currently do more than one boundary in each zone without over-writing itself.


Last updated 18 Dec 2006