Authors: William M. Chan and Pieter G. Buning
Date: March, 2006.
MIXSUR and OVERINT are used to perform flow coefficient computation and analysis on overset grids.
Chan, W. M. and Buning, P. G., User's Manual for FOMOCO Utilities - Force and Moment Computation Tools for Overset Grids , NASA TM 110408, July, 1996.
Details of the hybrid grid generation algorithm are found in
Chan, W. M. and Buning, P. G., Zipper Grids for Force and Moment Computation on Overset Grids, AIAA Paper 95-1681, in Proceedings of the AIAA 12th Computational Fluid Dynamics Conference, San Diego, California, June, 1995.
Click here for notes on using OVERINT for incompressible flow solutions.
Comments, questions, bug reports can be sent to wchan@nas.nasa.gov.
mixsur < [input parameters filename] > [output messages filename]
overint < [input parameters filename] > [output messages filename]
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Description File Type Filename
------------------------------------------------------------------------------------
Surface or volume grids * PLOT3D unformatted multiple grid file grid.in
Solution Q file * PLOT3D unformatted multiple grid file q.save
Input parameters (STDIN) ** ASCI
------------------------------------------------------------------------------------
* must supply at least 2 planes from all walls for viscous force computation
** the same input parameters file is used to run both MIXSUR and OVERINT
------------------------------------------------------------ Filename Description ------------------------------------------------------------ ib.com surface quads zips.com surface triangles bnds.com boundaries of triangulated regions ------------------------------------------------------------MIXSUR also writes a CART3D surface triangulation file called grid.i.tri over the entire surface domain. This triangulation consists of all the quads and triangles on the hybrid surface.
MIXSUR also writes a PLOT3D surface grid file with domain connectivity iblanks grid.ib. This file can be used to look at surface iblanks before integration iblanks are introduced.
MIXSUR also writes a PLOT3D fake Q file q.gmm for the geometric moments about (XMC,YMC,ZMC), the moment reference center prescribed in the mixsur input file. The vector sum of the moments of each cell about (XMC,YMC,ZMC) is stored in Q2,Q3,Q4. Functions in this file can be visualized with grid.ibi as the grid file.
Q1 = geometric moment in x (fun 100) Q2 = geometric moment in x (fun 160) Q3 = geometric moment in y (fun 161) Q4 = geometric moment in z (fun 162) Q5 = geometric moment in x (fun 163)
OVERINT can reads the above grid.i.tri file and outputs an annotated CART3D triangulation file called grid.i.triq which contains the grid plus 11 q dependent flow variables on the triangulated surface:
q1 = Cp
q2-q6 = rho, rho u, rho v, rho w, e
q7 = laminar viscosity
q8-10 = zeta derivative of u,v,w
q11 = wall normal grid spacing
OVERINT also writes the following files for further analysis:
q.sur Q on surface
q.pfr Fake Q file for local pressure force coef. components (xyz axes)
q.vfr Fake Q file for local viscous force coef. components (xyz axes)
using integration iblanks only (gaps in zipper regions)
q.sfr Fake Q file for local viscous force coef. components (xyz axes)
using domain connectivity iblanks only (no gaps in zipper regions).
Q5 in this file is the skin friction coefficient
pfr.com PLOT3D command file for q.pfr (xyz axes)
vfr.com PLOT3D command file for q.vfr (xyz axes)
sfr.com PLOT3D command file for q.sfr (xyz axes)
The q files q.sur, q.pfr q.vfr can be read with grid.ibi as the grid file. The q file q.sfr should be read with grid.ib as the grid file. The q variables in q.pfr, q.vfr, q.sfr are (PLOT3D function numbers are given in parenthesis):
Q1 = local cell area (fun 100) Q2 = pressure/viscous force coef in x (fun 160) Q3 = pressure/viscous force coef in y (fun 161) Q4 = pressure/viscous force coef in z (fun 162) Q5 = magnitude of pressure/viscous force coef (fun 163)
The PLOT3D command files plot Q5 by default. The force vector can be displayed with fun 202.
Version 1.1o (and later) of OVERINT also writes additional q files in wind axes components.
q.pfrw Fake Q file for local pressure force coef. components (wind axes) q.vfrw Fake Q file for local viscous force coef. components (wind axes) pfrw.com PLOT3D command file for q.pfr (wind axes) vfrw.com PLOT3D command file for q.vfr (wind axes) Q1 = local cell area (fun 100) Q2 = pressure/viscous force coef in drag dir. (fun 160) Q3 = pressure/viscous force coef in side dir. (fun 161) Q4 = pressure/viscous force coef in lift dir. (fun 162) Q5 = magnitude of pressure/viscous force coef (fun 163)
OVERINT computes the force vector element at the cell centers. Values at the node points are obtained by averaging neighboring unblanked cells. The coefficient Cf at a node is then computed by
Delta_f_node
Cf_node = -------------------------------------
0.5 * rho_inf * U_inf * U_inf * Aref
where Delta_f_node = the integral of the pressure or viscous stress tensor
at the node obtained by averaging over neighboring
unblanked cells
rho_inf = non-dimensional free stream density = 1
U_inf = non-dimensional free stream speed = Mach number
Aref = reference area assumed to be 1
The final Cf may have to be divided by a reference area which is assumed
to be 1 currently.
0.8, 2.0, 0.0, 0.0, 1.4, 507.0 FSMACH,ALPHA,BETA,REY,GAMINF,TINF
3 NREF
1.0, 1.0, 0.0, 0.0, 0.0 REFL,REFA,XMC,YMC,ZMC
1.0, 1.0, 0.0, 0.0, 0.0, 2.0, 1.0 REFL,REFA,XMC,YMC,ZMC,REFLY,REFLZ
1.0, 1.0, 0.5, 0.2, 0.0, 0.5, 1.0, 0.1 REFL,REFA,XMC,YMC,ZMC,XMH,YMH,ZMH
1 NSURF
4, 1 NSUB, IREF
1, 3, 1, -1, 2, -2, 1, 1 NG,IBDIR,JS,JE,KS,KE,LS,LE
2, 3, 19, 219, 1, -1 1, 1 NG,IBDIR,JS,JE,KS,KE,LS,LE
3, 3, 1, -1, 1, 14 1, 1 NG,IBDIR,JS,JE,KS,KE,LS,LE
3, 3, 19, 219, 14, -1 1, 1 NG,IBDIR,JS,JE,KS,KE,LS,LE
1 NPRI
3, 1 NU1,NU2
0 NCOMP
FSMACH > 0 Free stream Mach number
<= 0 Read free stream Mach number from q.save
ALPHA in range [-360,360] Angle of attack
outside of [-360,360] Read angle of attack from q.save
BETA in range [-360,360] Side slip angle
outside of [-360,360] Read side slip angle from q.save
REY > 0 Reynolds number for viscous flow
= 0 Inviscid flow assumed
< 0 Read Reynolds number from q.save
GAMINF = Free stream ratio of specific heats
TINF = Free stream temperature (Rankine)
NREF = Number of reference conditions
Repeat the following for each reference condition
{
REFL > 0 Reference length for fomo coefficients
<= 0 Use 1.0 as default reference length
REFA > 0 Reference area for fomo coefficients
<= 0 Use total integrated surface area from defined
subsets as default reference area
XMC,YMC,ZMC = X,Y,Z coordinates of moment axes center
REFLY,REFLZ = reference lengths for Y and Z moments
[if 2 extra real optional inputs are found]
XMH,YMH,ZMH = X,Y,Z coordinates of hinge moment axis vector head
[if 3 extra real optional inputs are found] *
}
NSURF = Number of surfaces to compute coefficients
Repeat the following for each integration surface
{
NSUB = Number of subsets that belong to the surface
IREF = Reference conditions set for the surface
Repeat the following for each subset
[
NG = Grid number
IBDIR = Direction of surface normal
(1 = +J, -1 = -J, 2 = +K, -2 = -K, 3 = +L, -3 = -L)
JS,JE = Start and end indices in J
KS,KE = Start and end indices in K
LS,LE = Start and end indices in L
]
NPRI = Number of subset pairs to specify priority
For each subset pair, enter
[
NU1 > 0, NU2 > 0 : Subset numbers within surface where subset NU1 will
be kept if it overlaps subset NU2
or
NU1 < 0, NU2 < 0 : Subset numbers within surface between which no zipper
grids should be created, e.g., abutting subsets
]
}
NCOMP = Number of components
Repeat the following for each component
{
[ component name ]
NIS = Number of integration surfaces for the component
IREF = Reference conditions set for the component
[ List of surface numbers for surfaces, negative numbers will contribute
negative forces/moments to the total ]
}
* If optional input XMH,YMH,ZMH are present, the hinge moment axis vector
base is taken from XMC,YMC,ZMC.