COMSOL 6.4 - Evaluating Expressions

Evaluating Expressions

If you want to evaluate the parameters, variables, or expressions in the model, use the function mphgetexpressions.

1

Evaluate the expressions of the parameters defined in the model:

expr = mphgetexpressions(model.param)

{'L' } {'9[cm]' } {'Length' } {[0.0900]} {'m' }

{'rad_1'} {'6[mm]' } {'Bolt radius' } {[0.0060]} {'m' }

{'tbb' } {'5[mm]' } {'Thickness' } {[0.0050]} {'m' }

{'wbb' } {'5[cm]' } {'Width' } {[0.0500]} {'m' }

{'mh' } {'6[mm]' } {'Maximum eleme…'} {[0.0060]} {'m' }

{'htc' } {'5[W/m^2/K]'} {'Heat transfer…'} {[ 5]} {'W/(m^2*K)'}

{'Vtot' } {'20[mV]' } {'Applied volta…'} {[0.0200]} {'V' }

2

You can evaluate a specific parameter expression by using the function mphevaluate. To evaluate the length of the busbar, L, in inches:

L = mphevaluate(model,'L','in')

The evaluation does not require an existing solution dataset in the model.

Code for Use with MATLAB®

% Evaluating Data at Arbitrary Points

Qtot = mphinterp(model,'ht.Qtot','coord',[5e-2;-2e-2;1e-3])

[Temp, unit]= mphinterp(model,'T','coord',[5e-2;-2e-2;1e-3],'unit','degF')

x0=0:5e-2/4:5e-2;

y0=0:-2.5e-2/4:-2.5e-2;

[x,y,z]=meshgrid(x0,y0,z0);

xx=[x(:),y(:),z(:)]';

Qtot = mphinterp(model,'ht.Qtot','coord',xx);

Qtot = reshape(Qtot,length(x0),length(y0),length(z0))

% Evaluating Data at Node Points

data = mpheval(model,'V')

data2 = mpheval(model,{'T' 'V'})

data3 = mpheval(model,'T','refine',2)

plot3(data3.p(1,:),data3.p(2,:),data3.p(3,:),'.');

plot3(data2.p(1,:),data2.p(2,:),data2.p(3,:),'.r');

data4 = mpheval(model,{'ec.normJ'},...

'edim',2,'selection',43)

% Global Evaluation and Integration

Vtot = mphglobal(model,'Vtot')

Q = mphint2(model,'ec.Qh','volume','selection',1)

[I unit] = mphint2(model,'ec.normJ','surface','selection',43)

maxT = mphmax(model,'T','volume','selection',1)

maxT = mphmax(model,'T','surface','selection',43)