Hi Dieter,

This seems to be a bug. I added it to the CodeBeamer
system we use for project planning and development.
http://openmodelica.ida.liu.se:8080/cb/issue/1012
I'll look into it.

Cheers,
Adrian Pop/

dieter wrote:
Hi,

I've got strange results with my overall model, even though the isolated
classes seem to work reasonably while testing.  Basically I'd like to
simulate a hydraulic circuit, with a pump flow changing in time and
subsequent flow resistances.

I reduced the problem to the following 3 primitive classes:

connector Port
  Real pressure;
  flow Real flowrate;
end Port;

model Pipe
  Port port;
  parameter Real a = 1;
equation
  port.pressure = port.flowrate * a;
end Pipe;

model Pump
 Port port;
equation
  port.flowrate = -( time - port.pressure);
end Pump;

//------------------------------

model Test
  Pump pu;
  Pipe pi;
equation
  connect(pu.port,pi.port);
end Test;

// simulate(Test);

Probably I've some severe misconceptions about coupling of the
components because the model does not reproduce the analytical solution:

  pi.flowrate = time/(1+a)

Results are basically constant (except for the time variable). There is
only a step change at the last time step!?

Where am I wrong?  Without your help, I'm totally stuck now!  (I'm using
version 1.4.4 of OM.)

      Dieter

--
    Best wishes

    H. Dieter Wilhelm
    Darmstadt, Germany

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