Invalid Cp Error after running Program With UDF

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  • Last Post 10 January 2020
atulsbhat posted this 17 December 2019

PROBLEM EXPLANATION : A NATURAL CONVECTION PROBLEM

Geometry : 2D Rectangular Flat Plate

Link for all My Files

https://drive.google.com/drive/folders/1v-cl_aCg5rN6EjibgOcT8vE0ybGxsE-D?usp=sharing

SOLVER: PRESSURE BASED,STEADY STATE , LAMINAR, SINGLE PHASE AND WITH ENERGY MODEL

GRAVITY: Y= -9.81

MATERIAL PROPERTIES: UDF (CELL BASED)

BOUNDARY CONDITIONS:

ISO (WALL) = 649.16 K (Near Critical Region TEMP) {Non LINEAR}

VELOCITY INLET= 0.0001 m/sec and 643.16 K

PRESSURE OUTLET: 22500000 (No Back Flow)

Method :COUPLED AND ALL RELAXATION FACTORS UNDER 0.8

UDF IS ATTACHED in the link above(NAMED PRO)

ERRORS WHICH I GOT; INVALID CP (I SET TEMP BOUNDS RIGHT)

Regards ATUL S

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rwoolhou posted this 10 January 2020

And if you overlay polynomial on top?  

atulsbhat posted this 09 January 2020

Nature of Graphs Sir

Regards

 

rwoolhou posted this 08 January 2020

If you're using polynomials with that many significant figures it's very likely that single/double precision and rounding error will generate significant errors.  Post an image of what the curve should look like. 

atulsbhat posted this 08 January 2020

Hello

I did not find any error but the property plot at end of my results, Showed me different set of properties, Well I cross checked all polynomials again , The polynomials seemed correct but properties fed into fluent didnt match with the Polynomial properties.. 

Regards

ani4377 posted this 07 January 2020

Can you then start debugging a bit by setting some properties constant and focusing on the one causing the issue?

Sir I am facing the same kind of error.

Can you please take a look at my post.

Thank you.

Anirudh

ani4377 posted this 07 January 2020

Dear Atul, 

Did you find the reason for error?.

Regards 

Anirudh

abenhadj posted this 17 December 2019

Can you then start debugging a bit by setting some properties constant and focusing on the one causing the issue?

Best regards, Amine

atulsbhat posted this 17 December 2019

Continuation.....

DEFINE_PROPERTY(cell_ktc, c, t) 

double T3 = C_T(c, t); 

double ktc;

if (635.00< T3 <=647.95)

{

ktc = (9.67327651787E-010*pow(T3,3)+ 1.07198980062E-006*pow(T3,2)-2.65628458181E-003*T3+1.00798585123E+000)/(5.00871983799E-009*pow(T3,3)-4.30553217646E-006*pow(T3,2)-8.56213098793E-004*T3+1);

}

else if (647.95< T3 <=648.73)

{

ktc = (-3.15665107745E-011*pow(T3,4)+5.74316328609E-008*pow(T3,3)-8.00570356905E-005*pow(T3,2)+6.58380991564E-002*T3-1.91080817698E+001)/(-1.88933190656E-007*pow(T3,3)+2.47518298176E-004*pow(T3,2)-8.26013714844E-002*T3+1);

}

else if (648.73< T3 <=649.10)

{

ktc = (9.21882104159E-010*pow(T3,3)+9.66700804229E-007*pow(T3,2)-2.41830902924E-003*T3+9.10302469777E-001)/(6.85095548536E-009*pow(T3,3)-6.51237771764E-006*pow(T3,2)-1.99926781030E-004*T3+1);

}

else if (649.10< T3 <=649.90)

{

ktc = (1.55340145958E-009*pow(T3,3)-2.08750317819E-006*pow(T3,2)+7.41797773475E-004*T3-2.68104657893E-002)/(3.01622383420E-011*pow(T3,3)+2.30136429280E-006*pow(T3,2)-3.04713864718E-003*T3+1);

}

else if (649.90< T3 <=660.00)

{

ktc = (1.57649522842E-010*pow(T3,3)+2.60321568704E-007*pow(T3,2)-5.21436191042E-004*T3+1.85693253101E-001)/(6.17253403657E-009*pow(T3,3)-5.52538004836E-006*pow(T3,2)-5.54654898842E-004*T3+1);

}

else

{

ktc = 0.15000;

}

return ktc; 

}

DEFINE_PROPERTY(cell_viscosity, c, t) 

double T4 = C_T(c, t); 

double mu_lam;

if (635.00< T4 <=647.20)

{

mu_lam = (9.89197719095E-015*pow(T4,4)-1.71009457131E-011*pow(T4,3)+9.33538304205E-009*pow(T4,2)-1.41644707543E-006*T4-9.28741686026E-005)/(-1.53533206630E-003*T4+1);

}

else if (647.20< T4 <=648.60)

{

mu_lam = (3.99280946668E-013*pow(T4,3)-1.98818294190E-010*pow(T4,2)-3.35610542542E-007*T4+1.92473554834E-004)/(-1.53822789587E-003*T4+1);

}

else if (648.60< T4 <=648.80)

{

mu_lam = (4.49491045673E-011*pow(T4,2)-5.82458544750E-008*T4+1.88689994165E-005)/(2.09494866252E-009*pow(T4,3)-3.38328960437E-007*pow(T4,2)-2.20364870424E-003*T4+1);

}

else if (648.80< T4 <=649.10)

{

mu_lam = (-3.70888390134E-016*pow(T4,4)-2.66822899344E-013*pow(T4,3)+2.04526782970E-010*pow(T4,2)+4.75118757913E-007*T4-2.55763296559E-004)/(2.20110380648E-009*pow(T4,3)-6.08541480188E-007*pow(T4,2)-2.07309915781E-003*T4+1);

}

else if (649.10< T4 <=660.00)

{

mu_lam = (-1.05232848074E-014*pow(T4,4)+1.59353912056E-011*pow(T4,3)-4.11811500648E-009*pow(T4,2)-3.32793940923E-006*T4+1.40518231742E-003)/(-1.54325740965E-003*T4+1);

}

else

{

mu_lam = 0.000027000;

}

return mu_lam; 

}

 

atulsbhat posted this 17 December 2019

#include "udf.h"

DEFINE_PROPERTY(cell_density, c, t) 

double T2 = C_T(c, t); 

double rho;

if (635.00< T2 <=647.65)

{

rho = (-1.80375321498E-008*pow(T2,3)+4.37725881273E-003*pow(T2,2)-5.72870568035E+000*T2+1.87919262419E+003)/(5.73224251694E-009*pow(T2,3)-5.29420035132E-006*pow(T2,2)-5.19145559843E-004*T2+1);

}

else if (647.65< T2 <=648.70)

{

rho = (3.17383063793E-005*pow(T2,3)-4.67841673791E-002*pow(T2,2)+2.04434456269E+001*T2-2.23825052795E+003)/(6.58499450671E-009*pow(T2,3)-6.85372588417E-006*pow(T2,2)+1.33555488262E-004*T2+1);

}

else if (648.70< T2 <=649.00)

{

rho =(-4.34313022431E-005*pow(T2,3)+3.32633967077E-002*pow(T2,2)+1.16448492280E+001*T2-9.69578668950E+003)/(-8.21772033015E-009*pow(T2,3)+1.25803346920E-005*pow(T2,2)-6.24451347023E-003*T2+1);

}

else if (649.00< T2 <=660.00)

{

rho = (-9.94061577245E-007*pow(T2,3)+2.29499012449E-003*pow(T2,2)-1.71573797723E+000*T2+4.18604178695E+002)/(1.54441783415E-009*pow(T2,3)+4.23867511741E-007*pow(T2,2)-2.46639558372E-003*T2+1);

}

else

{

rho = 145;

}

return rho; 

}

DEFINE_SPECIFIC_HEAT(cell_SpecificHeat, T, Tref, h, yi)

{  

double cp;

if (635.00< T <=648.00)

{

cp=(-1.22158459347E-003*pow(T,3)+2.17569323612E+000*pow(T,2)-1.29281382835E+003*T+2.56632684171E+005)/(-1.54130619189E-003*T+1);

}

else if (648.00< T <=648.73)

{

cp=(3.55323794766E-004*pow(T,3)-4.48432744279E-001*pow(T,2)+ 1.33037573218E+002*T+5.40783052792E+003)/(4.28000889300E-012*pow(T,4)+2.41784831000E-010*pow(T,3)-3.34155028245E-006*pow(T,2)-6.43985888337E-004*T+1);

}

else if (648.73< T <=649.50)

{

cp=(-5.18823303098E-008*pow(T,4)+8.61428212182E-004*pow(T,3)-1.43401674862E+000*pow(T,2)+8.29938510799E+002*T-1.60895776843E+005)/(4.17611916514E-009*pow(T,3)-3.04175710540E-006*pow(T,2)-1.32571651328E-003*T+1);

}

else if (649.50< T <=660.00)

{

cp=(3.63087828676E-007*pow(T,4)-5.05376552107E-004*pow(T,3)+7.74302775445E-002*pow(T,2)+1.42466716874E+002*T-5.13360638841E+004)/(6.70506677622E-009*pow(T,3)-6.23021496014E-006*pow(T,2)-3.21570998725E-004*T+1);

}

else

{

cp = 10000;

}

*h = cp*(T-Tref);

return cp; 

}

 

abenhadj posted this 17 December 2019

As ANSYS employee I do ignore attachments and links to Deive ObeDrive etc...

Paste your UDF here. Just for superficial verification as we do not debug UDFs

Best regards, Amine

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