Description

EX_ELECTROSTATICS1 Electrostatic test example.

[ FEA, OUT ] = EX_ELECTROSTATICS1( VARARGIN ) Electrostatics test example.

Accepts the following property/value pairs.

Input       Value/{Default}        Description
-----------------------------------------------------------------------------------
sfun        string {sflag2}        Shape function for pressure
iplot       scalar 0/{1}           Plot solution (=1)
                                                                                  .
Output      Value/(Size)           Description
-----------------------------------------------------------------------------------
fea         struct                 Problem definition struct
out         struct                 Output struct

Code listing

 cOptDef = { 'sfun',     'sflag2';
             'iplot',    1;
             'tol',      6e-3;
             'fid',      1 };
 [got,opt] = parseopt(cOptDef,varargin{:});
 fid       = opt.fid;


% Geometry and grid generation.
 fea.sdim = { 'x' 'y' };
 fea.grid = rectgrid(10);


% Problem definition.
 fea = addphys( fea, @electrostatics );
 fea.phys.es.eqn.coef{1,end} = { 2 };
 fea.phys.es.eqn.coef{2,end} = { 3 };
 fea.phys.es.eqn.coef{3,end} = { 4 };
 fea.phys.es.eqn.coef{4,end} = { 5 };
 fea.phys.es.sfun            = { opt.sfun };

 fea.phys.es.bdr.sel = [2 3 3 4];
 fea.phys.es.bdr.coef{3,end}{1,2} =  1;
 fea.phys.es.bdr.coef{3,end}{1,3} = -3;

% Parse and solve problem.
 fea       = parsephys( fea );
 fea       = parseprob( fea );
 fea.sol.u = solvestat( fea, 'fid', opt.fid );   % Call to stationary solver.


% Postprocessing.
 if( opt.iplot>0 )
   figure
   postplot( fea, 'surfexpr', 'V' )
   title( 'Electric potential' )
 end


% Error checking.
 V = intsubd( 'V', fea );
 D = intbdr( fea.phys.es.bdr.vars{2,2}, fea, 1:4 );
 out.err = [ abs(V-1.25)/1.25;
             abs(D+5)/5  ];
 out.pass = all( out.err < opt.tol );


 if ( nargout==0 )
   clear fea out
 end