POGS Version 20.6

Users are highly encouraged to work through the EPOGS tutorial under chimera3.0/tutorials/epogs.

• rootname.gcomp * - geometric component data file containing list of faces belonging to each geometric component
• rootname.i.tri * - an unstructured surface triangulation (one entity in intersected CART3D.i.tri format)
• rootname.triq - an unstructured surface triangulation with u,v parameter values at vertices of each face (NFACE entities in CART3D .triq format)
• rootname.uvin * - a set of structured surface patches from forward evaluation of auto-determined parameter space locations driven by max dihedral angle, max cell size, and max chordal deviation inputs. Iblanks at vertices are used to indicate trimmed regions with 1: vertex is on geometry, 0: vertex is outside geometry (NFACE surface grids in PLOT3D format)
• rootname.uv - PLOT3D function file containing u,v values for vertices in rootname.uvin (fun 1 = u value, fun 2 = v value)
• rootname.cur * - discretized edges on geometry (NEDGE surface curves in PLOT3D format)
• rootname.cuv - PLOT3D function file containing edge vertex u,v values for each edge (fun 1,2 = u,v on face 1 associated with edge, fun 3,4 = u,v on face 2 associated with edge, u=v=0 if face 2 is empty as on open boundary)
• rootname.topo * - ASCII text file containing topological information for edges and faces
• rootname.pogs.i * - ASCII text file containing input parameters for running pogs
• rootname.frm.gcomp - geometric components data file with reduced face list if faces are removed for open geometry cases

1. Generate meshes and input files for a single body.
2. Assemble meshes and input files for multiple bodies with multiplicity.
3. Split meshes and input files for a grid system where one or more grid block's x,y,z,ib data exceed 32-bits. Each mesh in the resulting split-grid system will fit inside a 32-bit record
.

Generation of grid system and various input files for single body

  pogs [-arcse arc] [-mdvopt vopt] [-nopro] [-nosplitg] [-noautosplay] [-oflbox] [-genbox boxopt]  
       [-dcfmix] [-dcfpogs] [-dcfxry] [-xdfrac xf] [-newnamlst] [-start startloc] [-stop stoploc] < pogs.i


Assembly of grid system and various input files for multiple-bodies with multiplicity
 
  pogs -combinebods nbody -bodymult bmults -bodyname bnames


Splitting of meshes and input files for a grid system with large single grid block(s)
 
  pogs -splitsys -npmaxsp npsp

All arguments are optional. If omitted, the defaults in the following table are used. A log file called "pogs.log" is automatically generated that contains the most recent command line arguments.

Argument	Description	Default
arc	Arc length for auto-activation of thin face logic (typically set to arc length of finite-thickness trailing edge)	not activated
vopt	Near-body volume grid normal marching distance option (1=constant, 2=variable)	2
nopro	Deactivate projection to geometry defined in input stp, igs or egads file. Starting point does not require running egads2srf first provided the following files are supplied: rootname.{gcomp,i.tri,uvin,cur,topo,pogs.i}	project to geometry
nosplitg	Turn off automatic grid splitting of large single block grids with grid sizes exceeding 32-bit record marker limit. Write all volume grid files with unsplit grids in plot3d multiple grid binary format	auto split
noautosplay	Deactivate auto splay adjustment scheme in near-body volume grids to improve adjacent mesh overlap	auto splay activated
oflbox	Generate off-body Cartesian grids using OVERFLOW option	not activated
boxopt	Off-body Cartesian grid option (2=single box grid with uniform core and stretched outer region to far field, 4=one box grid for each component, 5=same as 4 plus single encompassing box grid, 6=same as 5 plus telescoping layers of box grids extending to far field	5
dcfmix	Activate mixed-mode for domain connectivity: near-body connectivity performed in pogs (output XINTOUT/CINTOUT), off-body connectivity performed by flow solver	activated
dcfpogs	Domain connectivity performed by pogs for entire volume grid system (output XINTOUT/CINTOUT)	not activated
dcfxry	Domain connectivity to be performed manually using X-ray hole cut approach: X-ray maps have to be manually generated; first estimate of hole-cut instructions written to XRINFO blocks in OVERFLOW nameless input file	not activated
xf	Hole-cut offset distance for off-body grids = xf x local near-body volume grid marching distance (0.0 < xf < 1.0)	0.5
newnamlst	Activate new namelist format with reduced input for auto-generated OVERFLOW nameless input file (version ? or newer)	not activated
startloc	Starting location for running pogs. Allowed options: volgen (needs go.sur, go.sub, go.bc), boxgen (needs, nb.vol, go.sub, go.bc), vdocona (needs go.vol, go.sub, go.bc)	none-specified => starting from surface mesh generation
stoploc	Stopping location for running pogs. Allowed options: edgearc, go.sur, nb.vol, go.vol, ga.vol. Advanced users: splitr.cur, fmrecon.sur, thinf.sur nm.sur, em2.cur, enm.sur, gs.sur minhole.	none-specified => going to end of domain connectivity
nbody	Number of disjoint bodies in configuration to be assembled. Files for each body assumed to be located in directories b1, b2, ... b[nbody]	1
bmults	String containing nbody integers separated by commas for specifying multiplicity of each body (e.g., "1,4,4" for body 1 with multiplicity 1, bodies 2 and 3 with multiplicity 4)	1
bnames	String containing nbody names separated by commas for specifying name of each body. Auto-generated grid names are based on the body names, body multiplicities and component names (e.g., "Mainbody,CCW-Blade,CW-Blade").	-
npsp	Maximum number of grid points allowed in a single grid. Grid splitting will occur automatically if the number of grid points exceeds npsp.	32000000 (32 million)

The pogs workflow for creating the grid system and input files for a single body is as follows ([n]=001 for body 1, ...).

   1. Generate surface mesh system with iblanks (node, edge and face meshes) stored in go.sur by
 
      pogs [args] -stop go.sur < rootname.[n].pogs.i >! p.o
 
   2. Generate near-body volume mesh system stored in nb.vol by restarting from surface grids step
 
      pogs [args] -start volgen -stop nb.vol < rootname.[n].pogs.i >! p.o
 
   3. Perform repairs on mesh overlap or negative Jacobian by substituting manually repaired grids into nb.vol.
      Adjustments in the go.sub file may be needed if grid dimensions are altered.

   4. Generate off-body volume mesh system by restarting from near-body volume grids step (near and off-body volume grid system stored in go.vol)
 
      pogs [args] -start boxgen -stop go.vol < rootname.[n].pogs.i >! p.o
 
   5. Compute domain connectivity data by restarting from off-body volume grids step (final volume grid system with hole-cut blanks stored in ga.vol)
 
      pogs [args] -start vdocona -stop ga.vol < rootname.[n].pogs.i >! p.o
 

 
     pogs -combinebods nbody -bodymult bmults -bodyname bnames

• go.sur
• go.vol
• go.xry
• XINTOUT_NOGBOX
• over.namelist
• fomoco.i

It is assumed the go.vol each subdirectory contains one off-body box grid in the last slot that will be removed in the combinebods process. This option will create the following files for the combined grid system.

• Surface grid file (grid.sur)
• Volume grid file (grid.in)
• X-ray map file (xrays.in)
• Domain connectivity data (XINTOUT/CINTOUT)
• OVERFLOW namelist input (over.namelist)
• Component aerodynamic loads computation input file for mixsur/overint or usurp (fomoco.i)

Run pogs with the -splitsys option to create a split-grid system where all grids fit within a 32-bit record marker. The maximum number of grid points allowed in a single grid can be specified using the -npmaxsp command line input. Grid and input files for the split-grid system are named nb.sp.vol, go.sp.vol, ga.sp.vol, CINTOUT_NOGBOX.sp, fomoco.sp.i, over.sp.namelist.

      pogs -splitsys -npmaxsp npsp
    

The input file for FOMOCO forces/moments computation tools MIXSUR and OVERINT are created in fomoco.i. Default components are defined from the specified geometric components in rootname.[n].gcomp.

Useful data for manual hole-cutting using X-rays is provided in xrinfo.txt. Information includes list of grids belonging to each component, and list of collar grids connected to each component.

The volume mesh domain connectivity function in pogs creates both an XINTOUT and a CINTOUT file containing the domain connectivity iblanks, fringe points and donor stencils data. Newer versions of OVERFLOW accepts the CINTOUT format which is the same as the INTOUT format. These files are used when the -dcfmix or the -dcfpogs options are activated.

• go.sur - overset surface mesh system
• nb.vol - overset near-body volume mesh system
• go.vol - overset near-body and off-body volume mesh system
• ga.vol - overset near-body and off-body volume mesh system with iblanks marking hole-cuts from domain connectivity
• XINTOUT/CINTOUT - volume mesh fringe points, donor stencil data and iblanks
• XINTOUT_NOGBOX/CINTOUT_NOGBOX - same as XINTOUT/CINTOUT but omitting last grid (enclosing box grid) for use in OVERFLOW for mixed-mode operation
• over.namelist - OVERFLOW namelist input file with boundary conditions and auto-generated grid names based on component that the grid belongs to
• fomoco.i - input parameters file for component aerodynamic loads computation using MIXSUR/OVERINT or USURP

• splitr.cur - discretized edges from BREP geometry
• nm.cur - initial curves for node meshes
• em2.cur - initial curves for edge meshes
• nm.sur - node surface meshes
• emn.sur - edge and node surface grids created by hyperbolic or algebraic marching before LCBC iterations
• gs.sur - edge and node surface grids created by hyperbolic or algebraic marching after LCBC iterations
• nemfrin.sur - node & edge meshes after domain connectivity between node & edge meshes (orphan points left are to be covered by face meshes)
• nemfrin2.sur - node & edge meshes after domain connectivity with face meshes (orphan points are used to guide face mesh local refinement)
• fmdonor.sur - face meshes where donor cell vertices for edge+node mesh fringe points are marked by ib=101
• fmretract.sur - face meshes after iblanks retraction
• fmreduc.sur - face meshes after dimensions reduction

   *** Full-body (isym=0), filename: rootname.topo ***

   read(*,*) ism,nedge,nface,scale
   do i=1,nedge
      read(*,*) enum,face1,sense1,face2,sense2
   enddo


   *** Symmetric-body full-body topology (isym=11/12/13), filename: rootname.topo ***

   read(*,*) isym,nedge,nface,scale
   do i=1,nedge
      read(*,*) enum,face1,sense1,face2,sense2,etype,esymp
   enddo


   *** Symmetric-body half-body topology (isym=11/12/13), filename: rootname.half.topo ***

   read(*,*) isym,nedgeh,nfaceh,scale
   do i=1,nedgeh
      read(*,*) enum,face1,sense1,face2,sense2
   enddo
   read(*,*) nfaceh,nface
   do i=1,nfaceh
      read(*,*) idnew,idorig,fsymp
   enddo
   read(*,*) nopen
   do i=1,nopen
      read(*,*) eid, esym
   enddo