Hi Everyone,

I have a problem that I am trying to solve.  When I try to simulate the following code:


model Test
  parameter  Real m(unit = "kg/s", min = 0) = 9.96720e-005;
  parameter Real Pdown(unit = "bar", min = 0) = 2.048153 - 0.6209;
  parameter Real Cd = 0.7;
  parameter Real D(unit = "m") = 0.0005588;
  parameter Real Tup(unit = "°C") = 20.5;
  parameter Real g(unit = "Dimensionless") = 1.401;
  parameter Real Rspecific(unit = "J/(kgK)") = 287.1;
  constant Real PI = 3.14159265;
 
  Real Pup ;
  Real Aorifice(unit = "m2");
  Real Pcr;
  Real P;
equation
  Aorifice = PI * (D / 2) ^ 2;
  Pcr = (2 / (g + 1)) ^ (g / (g - 1));
  P = Pdown / Pup;
  if P > Pcr then
  m = Cd * Aorifice * 100000 * Pup / sqrt(Tup + 273.15) * sqrt(g / Rspecific * 2 / (g - 1) * ((Pdown / Pup) ^ (2 / g) - (Pdown / Pup) ^ ((g + 1) / g)));
  else
m = 1000 * Cd * Aorifice * 100000 * Pup / sqrt(Tup + 273.15) * sqrt(g / Rspecific * (2 / (g + 1)) ^ ((g + 1) / (g - 1)));
  end if;
end Test;

I get the following error message that says:

record SimulationResult
    resultFile = "Test_res.mat",
    messages = "stdout            | warning | While solving non-linear system an assertion failed.
|                 | |       | | The non-linear solver tries to solve the problem that could take some time.
|                 | |       | | It could help to provide better start-values for the iteration variables.
|                 | |       | | For more information simulate with -lv LOG_NLS
stdout            | warning | Non-Linear Solver try to handle a problem with a called assert.
"
end SimulationResult;
OMC-ERROR:
"Warning: Iteration variables with default zero start attribute in nonlinear equation system:
         Pup:VARIABLE() .Test, .Real type: Real
         P:VARIABLE() .Test, .Real type: Real
"

I was wondering if someone knew how to overcome the issue and how to set the start value for Pup

Thank you

Malen