=========================================================================
			WIND Test Case
=========================================================================
------------------------------------------------------------------
	Diffusing Pipe Flow
------------------------------------------------------------------
This test case computes incompressible turbulent flow in a conical
diffuser, and is referred to as the Fraser (flow A) case 
from the 1968 AFOSR-IFP Stanford Conference on Computation of
Turbulent Boundary Layers. The geometry consists of a straight
section of pipe followed by a 5 degree half-angle conical diffuser.
The core Mach number at the diffuser entrance is 0.15 (52 m/s), and
the Reynolds number based on pipe diameter is approximately 500,000.
(This is an NPARC model validation case, which can be found at
http://info.arnold.af.mil/nparc/model/subsdif/.)
------------------------------------------------------------------
	Input Parameters
------------------------------------------------------------------
We assumed the gas is ideal air (R = 1714.48 ft^2/s^2*deg R and
a ratio of specific heats = 1.4).  The following freestream 
static conditions were used:
Mach Number = 0.15
Pressure = 14.7 psi
Temperature = 530 R
Using the viscosity obtained from Sutherland's law, the 
resulting Reynolds number is 1.034176E06/ft.
The CFL number was set as follows:
	CFL = 0.5 for the first 2000 iterations
        CFL = 1.3 for the remaining iterations
The Spalart-Allmaras turbulence model was used.
The JMAX boundary was set to CONFINED OUTFLOW in GMAN.  In the
WIND input data file, the corresponding mass flow rate was set
to 2.453256 lbm/sec; this value was computed from the experimental
data.
------------------------------------------------------------------
	Grid
------------------------------------------------------------------
The grid used is structured and has 121 axial points and 71 radial
points. It is packed at the wall such that y+=1 at the first point
from the wall.  It is also packed axially at the inflow boundary 
to resolve large axial flow gradients. 
The grid was obtained from the NPARC validation archive 
(http://info.arnold.af.mil/nparc/model/subsdif/case01/plotx1.bin).
The CFCNVT utility was used to convert plotx1.bin, which was in
PLOT3D format (2D/multigrid/formatted), to a .cgd file (subsdif.cgd)
which could be read by GMAN and WIND.
------------------------------------------------------------------
	Boundary Conditions
------------------------------------------------------------------
The boundary conditions, which were set using GMAN are:
(1) I1 - inflow
(2) IMAX - confined outflow
(3) J1 - inviscid wall
(4) JMAX - viscous wall
The units were set to feet.
The resulting grid and boundary condition file is subsdif.cgd.
The script file containing the above GMAN inputs is called 
gman.jou.
------------------------------------------------------------------
	Output Files
------------------------------------------------------------------
Wind produced an output listing file (subsdif.lis) and a solution
file (subsdif.cfl).  These were used to produce a residual history 
file (subsdif.resl2) via the RESPLT utility. CFPOST was used to
generate plot3d grid and solution files (subsdif.x.bin and
subsdif.q.bin, respectively) and a file containing the axial mass
flux distribution in the diffuser (subsdif.mflux).
------------------------------------------------------------------
	Comparison of Data
------------------------------------------------------------------
The WIND computed results are compared with experimental data, 
and with an NPARC solution, 
computed using the Spalart-Allmaras turbulence model.  The file 
velocity.ps contains velocity profiles at three locations in the
diffusing pipe section: x = 0.117, 0.381 and 0.642 m, where 
x = 0.0 m is the start of the diffusing section. The file cf.ps
contains a plot of the skin friction coefficient, and the file cp.ps
contains a plot of the static pressure coefficient. For the
velocity and static pressure coefficient profiles, the WIND
and NPARC curves are essentially coincident.  For the skin
friction in the upstream portion of the pipe, WIND predicts 
lower values than NPARC.
The WIND solution took about 60,000 iterations to reach 
convergence, where convergence is defined as the point where the
skin friction coefficient stops changing. (This was an eyeball 
estimate, obtained by examining skin friction plots.)  The NPARC
solution was started from a converged k-omega solution: the
k-omega calculation was run for 18,000 iterations, and the 
Spalart-Allmaras calculation was run for an additional 18,000 
iterations. No real attempt was made to optimize convergence
with either code.
Below is a list describing the files in this directory
README		This file
cf.ps		Plot of skin friction coefficient (PostScript format)
cfpost.jou	Script file of inputs for running CFPOST
cp.ps		Plot of static pressure coefficient (PostScript format)
gman.jou	Script file of inputs for running GMAN
resl2.ps	Plot of WIND residual history (PostScript format)
subsdif.cfl	WIND flow field data file (common file 3 format *)
subsdif.cgd	Grid (common file 3 format *)
subsdif.dat	WIND input data file
subsdif.lis	WIND list output file
subsdif.resl2   Residual history file (genplot format)
subsdif.q.bin   Plot3d solution file (IEEE unformatted)
subsdif.x.bin   Plot3d grid file (IEEE unformatted)
subsdif.mflux   Mass flux file (genplot format)
vel.ps          Plot of velocity profiles (PostScript format)
* See the "Common File Programmers Guide", by McDonnell Douglas 
Aerospace, St. Louis, Mo 63166.
If you have questions or comments about this case, please contact:
        Julianne Dudek, MS 5-11
        NASA Lewis Research Center
        21000 Brookpark Road
        Cleveland, OH 44135
        (216) 433-2188
        julie@lerc.nasa.gov