FEATool Multiphysics
v1.17.1
Finite Element Analysis Toolbox
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EX_NAVIERSTOKES13 3D Example flow past a cylinder.
[ FEA, OUT ] = EX_NAVIERSTOKES13( VARARGIN ) Sets up and solves stationary and laminar 3D flow past a cylinder. Accepts the following property/value pairs.
Input Value/{Default} Description ----------------------------------------------------------------------------------- rho scalar {1} Density miu scalar {0.001} Molecular/dynamic viscosity uin scalar {0.45} Magnitude of inlet velocity sf_u string {sf_hex_Q1nc} Shape function for velocity sf_p string {sf_disc0} Shape function for pressure solver string 'openfoam'/{'} Use OpenFOAM or default solver iplot scalar 0/{1} Plot solution and error (=1) . Output Value/(Size) Description ----------------------------------------------------------------------------------- fea struct Problem definition struct out struct Output struct
cOptDef = { ... 'rho', 1; 'miu', 0.001; 'uin', 0.45; 'nlev', 1; 'sf_u', 'sf_hex_Q1nc'; 'sf_p', 'sf_disc0'; 'tol', 0.2; 'solver', 'openfoam'; 'iplot', 1; 'fid', 1 }; [got,opt] = parseopt(cOptDef,varargin{:}); fid = opt.fid; % Geometry. fea.sdim = { 'x', 'y', 'z' }; gobj1 = gobj_block( 0, 2.5, 0, 0.41, 0, 0.41, 'B1' ); gobj2 = gobj_cylinder( [0.5 0 0.21], 0.05, 0.41, 2, 'C1' ); fea.geom.objects = { gobj1 gobj2 }; fea = geom_apply_formula( fea, 'B1-C1' ); % Grid generation. ns = 8*2^(opt.nlev-1); r = [0.05 0.06 0.08 0.11 0.15]; x = [0.41 0.5 0.7 1 1.4 1.8 2.2] + 0.3; for ilev=2:opt.nlev r = sort( [ r (r(1:end-1)+r(2:end))/2 ] ); x = sort( [ x (x(1:end-1)+x(2:end))/2 ] ); end grid1 = ringgrid( r, 4*ns, [], [], [0.5;0.2] ); grid2 = holegrid( ns, 2^(opt.nlev-1), [0.3 0.71;0 0.41], 0.15, [0.5;0.2] ); grid2 = gridmerge( grid1, 5:8, grid2, 1:4 ); grid3 = rectgrid( x, ns, [0.71 2.5;0 0.41] ); fea.grid = gridmerge( grid3, 4, grid2, 6 ); grid4 = rectgrid( 1, ns, [0 0.3;0 0.41] ); fea.grid = gridmerge( fea.grid, 10, grid4, 2 ); fea.grid = gridextrude( fea.grid, 5, 0.41, 2 ); fea.grid.p(3,:) = fea.grid.p(3,:) + 0.41; % Renumber boundaries to match geometry. fea.grid.b(3,fea.grid.b(3,:)==6) = -7; fea.grid.b(3,fea.grid.b(3,:)==5) = -8; fea.grid.b(3,fea.grid.b(3,:)==4) = -9; fea.grid.b(3,fea.grid.b(3,:)==7) = -10; [~,ind] = findbdr( fea, 'x<=sqrt(eps)', false ); fea.grid.b(3,ind) = 5; [~,ind] = findbdr( fea, 'x>=2.5-sqrt(eps)', false ); fea.grid.b(3,ind) = 3; [~,ind] = findbdr( fea, 'y<=sqrt(eps)', false ); fea.grid.b(3,ind) = 2; [~,ind] = findbdr( fea, 'y>=0.41-sqrt(eps)', false ); fea.grid.b(3,ind) = 4; [~,ind] = findbdr( fea, 'z<=sqrt(eps)', false ); fea.grid.b(3,ind) = 1; [~,ind] = findbdr( fea, 'z>=0.41-sqrt(eps)', false ); fea.grid.b(3,ind) = 6; fea.grid.b(3,fea.grid.b(3,:)==-7) = 7; fea.grid.b(3,fea.grid.b(3,:)==-8) = 8; fea.grid.b(3,fea.grid.b(3,:)==-9) = 9; fea.grid.b(3,fea.grid.b(3,:)==-10) = 10; fea.grid.s(:) = 1; if( strcmp(opt.solver,'openfoam') ) fea.grid = gridrefine( fea.grid, fid ); end % Problem definition. fea = addphys( fea, @navierstokes ); fea.phys.ns.eqn.coef{1,end} = { opt.rho }; fea.phys.ns.eqn.coef{2,end} = { opt.miu }; fea.phys.ns.sfun = { opt.sf_u opt.sf_u opt.sf_u opt.sf_p }; if( strcmp(opt.solver,'openfoam') ) [fea.phys.ns.sfun{:}] = deal('sflag1'); end % Boundary conditions. fea.phys.ns.bdr.sel(5) = 2; fea.phys.ns.bdr.coef{2,end}{1,5} = ['16*',num2str(opt.uin),'*(y*z*(0.41-y)*(0.41-z))/0.41^4']; fea.phys.ns.bdr.sel(3) = 4; fea.phys.ns.prop.artstab.iupw = 4; % Parse and solve problem. fea = parsephys( fea ); fea = parseprob( fea ); if( strcmp(opt.solver,'openfoam') ) logfid = fid; if( ~got.fid ), fid = []; end fea.sol.u = openfoam( fea, 'fid', fid, 'logfid', logfid ); fid = logfid; else fea.sol.u = solvestat( fea, 'fid', fid ); end % Postprocessing. if( opt.iplot>0 ) postplot( fea, 'sliceexpr', 'sqrt(u^2+v^2+w^2)' ) end % Error checking. s_tfx = ['nx*p+',num2str(opt.miu),'*(-2*nx*ux-nz*(uz+vx))']; s_cd = ['-2*(',s_tfx,')/(',num2str(opt.rho),'*',num2str(0.2),'^2*',num2str(0.1*0.41),')']; c_d1 = abs(intbdr(s_cd,fea,[7:10],10)); dp = evalexpr('p',[0.45 0.55;0.205 0.205;0.21 0.21],fea); out.err = [abs(c_d1-6.185333)/6.185333, ... abs(dp(1)-dp(2)-0.171007)/0.171007]; out.pass = all(out.err < [0.15 0.6]); if ( nargout==0 ) clear fea out end