4.6. NASA 网格生成程序
NASA Turbulence Modeling Resource 提供了大量实验和数值模拟数据。其中， 3D Hemisphere Cylinder Validation Case 和 3D ONERA M6 Wing Validation Case 两个示例中提供了三维网格的生成程序 Fortran 代码。
4.6.1. 代码说明和示例
以 ONERA M6 机翼为例 (图 4.6.1), NASA 提供了 图 4.6.2 所示的网格生成程序。 该程序在 AIAA-2018-1101 中进行了介绍。 报告 Hemisphere/Wing Grid Generation Codes 中也对以上程序进行了介绍。 代码链接为 wing_release_072319.tar.gz。
Note
此代码只能生成对称翼型的后掠机翼（结构、非结构）网格。
This code generates a 3D grid over a wing generated by a NACA00XX airfoil or by an airfoil defined by a set of discrete points (e.g., OM6 wing).
The wing grids are topologically equivalent to the hemisphere-cylinder grids.
In the mesh generation process, a surface mesh for a full-geometry hemisphere-cylinder configuration is generated first. This surface mesh is then mapped onto a wing: the cylinder is mapped onto the main wing and the hemisphere is mapped onto the wing tip. Each surface node is projected onto the airfoil section profile.
# Compile the HC-family grid generation program
gfortran -o hcf_wing hcf_wing_v5p0.f90
# Compile the coarsening program
gfortran -o hc_coarsening hcf_coarsening_v3p9.f90
# Generate a fine structured grid
# read in input.nml
./hcf_wing
# Generate coarse grids from the grid just generated
# read in input_coarsen.nml
./hcf_coarsening
# Convert .ugrid+.mapbc file to a CGNS file,
# where $HOME/cgnslib/ is the directory of the CGNS library installed.
%$HOME/cgnslib/bin/cgnstools/aflr3_to_cgns xxx.b8.ugrid xxx.cgns
图 4.6.2 ONERA M6 Grid
4.6.2. 控制文件
控制文件示例参见网站 3D ONERA M6 Wing Validation Case 。
机翼网格生成的控制文件 input.nml:
&input_parameters
target_reynolds_number = 14.6e6 !Target Reynolds number based on the root chord (=1.0 in the grid).
target_y_plus = 0.5 !Target y-plus value
igrid_type = 5 !1=prsm, 2=tets, 3=prsm/tets, 4=prsm/hex, 5=Strct
airfoil_type = 0 !airfoil_type: =0 discrete airfoil data, =1 NACA00XX
airfoil_data_file = "om6_wing_section_sharp.dat" !Datafile for the discrete airfoil data ; not used if airfoil_type = 1
tr = 0.5625159852668158 !Taper ratio = (tip chord)/(root chord)
beta = 29.9990 !Swept angle of LE line in degrees (not too large, please: e.g., < 40).
R_outer = 100 !Distance to outer boundary (=radius of the outer hemisphere)
nnodes_cylinder_input = 192 !Elements along the semi-wingspan
b = 1.476017976219800 !b = semi-span: per unit root chord.
nr_gs = 64 !# of Elements across the rounded tip /2 (-> HC: x=0 to 0.5)
nre = 704 !# of Elements in the radial direction (from wing to farfield)
wing_side = 2 !wing_side: =1 for left wing, =2 for right wing.
root_le_x = 0.0 !root_le_x: = x coordinate of the LE at the root.
stretching_tanh_towards_lete = 4.5 !Cluster points to LE/TE by a larger value.
generate_ugrid_file = T !T = Write a .ugrid file. (required by the coarsening program)
ugrid_file_unformatted = T !T = unformatted .ugrid/.ufmt, F = formatted .ugrid/.p3d
generate_p3d_ufmt_file = T !T = Write p3d file for a structured grid (only for 5=Strct).
generate_su2grid_file = F !T = Write a .su2 file (the native grid-format for Stanford's SU2).
generate_k_file = T !T = Write a 'k'-file (required by the coarsening program)
k_file_unformatted = T !T = unformatted .k file, F = formatted .k file.
generate_line_file_nc = T !T = Write node line files (required by the coarsening program)
generate_line_file_cc = T !T = Write cell line files (required by the coarsening program)
generate_tec_file_b = T !T = Write a boundary grid (Tecplot)
generate_tec_file_v = F !T = Write a volume grid (Tecplot)
/
! NOTE: The above parameters will generate a grid over an ONERA M6 wing.
! NOTE: Root chord will be normalized as 1.0 for any input airfoil data.
! NOTE: wing-side-change/root_le_x-shifting will be applied after
! a grid with unit wing-root chord is generated.
! NOTE: # of elements around the wing-section is automatically set as
! 6*(Elements along the hemisphere).
! NOTE: For regular coarsening, choose the input values such that
! (# of Elements along the the semi-wingspan) = 2^l
! 6*(# of Elements along the rounded tip) = 2^n
! (# of Elements in the radial direction) = 2^m
! where l, n, and m are integers.
! NOTE: To generate a .su2 grid file, set
! generate_su2grid_file = T
!
稀网格转换的控制文件 input_coarsen.nml:
&input_parameters
project = 'wing_strct'
tet2prism = F
ugrid_file_unformatted = T
k_file_unformatted = T
rmp_file_unformatted = T
prolong_file_unformatted = T
generate_su2grid_file = F !T = Write a .su2 file (the native grid-format for Stanford's SU2).
generate_tec_file_b = T
generate_tec_file_vol = F
generate_ntrl_partition_files = T !T = write natural-partition files.
generate_heff_vol_report = F !T = write volume and mesh spacing information file.
generate_nc_prolong_file = T !T = write NC prolongation information files.
generate_rmp_file = T !T = write files containing removed nodes.
generate_cc_prolong_file = T !T = write CC prolongation information files.
check_negative_elm_vol = T !T = check the negative element volumes.
check_non_planarity = T !T = check non-planarity for quad faces.
/
! NOTE: To generate a .su2 grid file, set
! generate_su2grid_file = T
!
! Input parameters below must match those in the input file used to generate the fine grid:
!
! ugrid_file_unformatted
! k_file_unformatted
!