Discussion Forum

Hi all,

I am trying to model a choked flow from a nozzle inside a duct. As the flow is choked and the subsequent pipe is diverging, the flow at the outlet will remain supersonic. I tried to model this situation using High Mach Number Flow, k-e interface but the following error message came up, does anyone know what might be the problem? Thanks!

error:

Failed to find a solution.
Segregated Step 1
Attempt to evaluate nonintegral power of negative number.
Function: ^
Failed to evaluate variable.
Variable: comp1.hmnf.kzz, Defined as: ((comp1.hmnf.k ref*((comp1.T/comp1.hmnf.Tk ref)^1.5))*(comp1.hmnf.Tk ref+comp1.hmnf.Sk s))/(comp1.T+comp1.hmnf.Sk s)
Failed to evaluate variable.
Variable: comp1.hmnf.kmean nitf, Defined as: 0.5*(comp1.hmnf.kzz+comp1.hmnf.krr)
Failed to evaluate variable.
Variable: comp1.hmnf.Pr, Defined as: (comp1.hmnf.Cp*comp1.hmnf.mu)/comp1.hmnf.kmean nitf
Failed to evaluate expression.
Expression: comp1.hmnf.Pr
Failed to evaluate operator.
Operator: mean, Geometry: geom1, Boundaries: 9-11, 14
Failed to evaluate expression.
Expression: mean(comp1.hmnf.Pr)
Failed to evaluate variable.
Variable: comp1.hmnf.Pr, Geometry: geom1, Boundaries: 9-11, 14
Failed to evaluate operator.
Operator: nif, Geometry: geom1, Boundaries: 9-11, 14
Failed to evaluate expression.
Expression: nif(comp1.hmnf.d w plus<(10/(comp1.hmnf.Pr^0.33333333333333331)),nojac(comp1.hmnf.Pr*comp1.hmnf.d w plus),comp1.hmnf.d w plus<sqrt((1000*comp1.hmnf.kappav)/comp1.hmnf.Prt),nojac((15*(comp1.hmnf.Pr^0.66666666666666663))-(500/(comp1.hmnf.d w plus^2))),nojac(((15*(comp1.hmnf.Pr^0.66666666666666663))+((comp1.hmnf.Prt*log(comp1.hmnf.d w plus))/comp1.hmnf.kappav))-(((comp1.hmnf.Prt*0.5)*(1+log((1000*comp1.hmnf.kappav)/comp1.hmnf.Prt)))/comp1.hmnf.kappav)))
Failed to evaluate expression.
Expression: if(comp1.hmnf.hasWF,nif(comp1.hmnf.d w plus<(10/(comp1.hmnf.Pr^0.33333333333333331)),nojac(comp1.hmnf.Pr*comp1.hmnf.d w plus),comp1.hmnf.d w plus<sqrt((1000*comp1.hmnf.kappav)/comp1.hmnf.Prt),nojac((15*(comp1.hmnf.Pr^0.66666666666666663))-(500/(comp1.hmnf.d w plus^2))),nojac(((15*(comp1.hmnf.Pr^0.66666666666666663))+((comp1.hmnf.Prt*log(comp1.hmnf.d w plus))/comp1.hmnf.kappav))-(((comp1.hmnf.Prt*0.5)*(1+log((1000*comp1.hmnf.kappav)/comp1.hmnf.Prt)))/comp1.hmnf.kappav))),0)
Failed to evaluate variable.
Variable: comp1.hmnf.Tplus, Defined as: if(comp1.hmnf.hasWF,nif(comp1.hmnf.d w plus<(10/(comp1.hmnf.Pr^0.33333333333333331)),nojac(comp1.hmnf.Pr*comp1.hmnf.d w plus),comp1.hmnf.d w plus<sqrt((1000*comp1.hmnf.kappav)/comp1.hmnf.Prt),nojac((15*(comp1.hmnf.Pr^0.66666666666666663))-(500/(comp1.hmnf.d w plus^2))),nojac(((15*(comp1.hmnf.Pr^0.66666666666666663))+((comp1.hmnf.Prt*log(comp1.hmnf.d w plus))/comp1.hmnf.kappav))-(((comp1.hmnf.Prt*0.5)*(1+log((1000*comp1.hmnf.kappav)/comp1.hmnf.Prt)))/comp1.hmnf.kappav))),0)
Failed to evaluate expression.
Expression: if(comp1.hmnf.hasWF,((comp1.hmnf.TWall-comp1.T)*comp1.hmnf.qwfc)/comp1.hmnf.Tplus,0)
Failed to evaluate variable.
Variable: comp1.hmnf.qwf, Defined as: if(comp1.hmnf.hasWF,((comp1.hmnf.TWall-comp1.T)*comp1.hmnf.qwfc)/comp1.hmnf.Tplus,0)
Failed to evaluate expression.
Expression: d(test(comp1.T)*comp1.hmnf.qwf,{test7})
Failed to evaluate Jacobian of expression.
Expression: test(comp1.T)*comp1.hmnf.qwf
Failed to evaluate Jacobian of expression.
Expression: (2*if(comp1.hmnf.hasWF,comp1.hmnf.qwf*test(comp1.T),0)*pi*r)*(dvol)
Returned solution is not converged.
- Feature: Stationary Solver 1 (sol1/s1)