[sidkamat]

Hello. I am trying to introduce a force in the DPM_BODY_FORCE macro in the DPM model. The force is dependent on the flow velocity so I want to incorporate the flow velocity into the equation. My code is:

DEFINE_DPM_BODY_FORCE(DEP,tp,i)
{
double beta=L/D;
double xi=beta/sqrt((beta*beta-1));
double c1=0.5*log((xi+1)/(xi-1));
double f=xi*((1-xi*xi)*c1*xi+xi);
double Fd=0;
if (TP_POS(tp)[0] >= 0.05)
{
if(i == 1)
{
Fd = -1* (pi * km * epsilon * D * D * L / 6) / (alpha / (alpha - 1) - f) * pow(V / log(R2 / R1), 2) * pow(1 / TP_POS(tp)[1], 3)+pi*mu*D*4* fabs(TP_VEL(tp)[1])*(pow(beta,2)-1)/((2*pow(beta,2)-1)*(log(beta+sqrt(pow(beta,2)-1))/sqrt(pow(beta,2)-1)-beta));
}
else if (i == 0)
{
Fd = -1*pi * mu * D * fabs(C_U(c,t)-TP_VEL(tp)[0]) * 8 * (pow(beta, 2) - 1) / ((2 * pow(beta, 2) - 3) * (log(beta + sqrt(pow(beta, 2) - 1)) / sqrt(pow(beta, 2) - 1) + beta));
}
}
return(Fd/TP_MASS(tp));
}

I am getting the following error during compilation:
error: use of undeclared identifier 'c'
error: use of undeclared identifier 't'

Is this because I am using the flow variables in a different macro that does not have the variables t & c in its declaration. If yes, how do I fix this.

Some help would be appreciated.

[Mohammad74]

Hi,
You have not defined c and t as variables in your macro, and thats what the error means. If you defined them somewhere else (like in another macro, in this source fille), and want to use their value here, you should define them as global variables in your source file. Which makes them visible to all the macros inside the said source file.

[thedal]

Originally Posted by sidkamat

Hello. I am trying to introduce a force in the DPM_BODY_FORCE macro in the DPM model. The force is dependent on the flow velocity so I want to incorporate the flow velocity into the equation. My code is:

DEFINE_DPM_BODY_FORCE(DEP,tp,i)
{
double beta=L/D;
double xi=beta/sqrt((beta*beta-1));
double c1=0.5*log((xi+1)/(xi-1));
double f=xi*((1-xi*xi)*c1*xi+xi);
double Fd=0;
if (TP_POS(tp)[0] >= 0.05)
{
if(i == 1)
{
Fd = -1* (pi * km * epsilon * D * D * L / 6) / (alpha / (alpha - 1) - f) * pow(V / log(R2 / R1), 2) * pow(1 / TP_POS(tp)[1], 3)+pi*mu*D*4* fabs(TP_VEL(tp)[1])*(pow(beta,2)-1)/((2*pow(beta,2)-1)*(log(beta+sqrt(pow(beta,2)-1))/sqrt(pow(beta,2)-1)-beta));
}
else if (i == 0)
{
Fd = -1*pi * mu * D * fabs(C_U(c,t)-TP_VEL(tp)[0]) * 8 * (pow(beta, 2) - 1) / ((2 * pow(beta, 2) - 3) * (log(beta + sqrt(pow(beta, 2) - 1)) / sqrt(pow(beta, 2) - 1) + beta));
}
}
return(Fd/TP_MASS(tp));
}

I am getting the following error during compilation:
error: use of undeclared identifier 'c'
error: use of undeclared identifier 't'

Is this because I am using the flow variables in a different macro that does not have the variables t & c in its declaration. If yes, how do I fix this.

Some help would be appreciated.

Two things:

1. Yes, you either declare c and t as global variable and calculate the flow variable but even if you declare it outside. I am not sure where the value of cell ID and thread pointer values you will get.

2. So, I suppose you use a cell loop to loop through all the cells and calculate the value I guess for which you have to define c and t inside the macro also.