openmodelica

I'd like to model a closed hydraulic cycle as one can find in the Modelica Standard Library/Fluid/Examples/HeatingSystem. With the heating system as well as with my (minimalistic) example I've got the same problem: The system is overdetermined. You can find the HeatingSystem as a "bad example" in the following lecture, so I guess this is a well known problem, but I don't really get the point. http://www.modprod.liu.se/MODPROD2011/1.252944/modprod2011-day2-talk3-Keynote-Francesco-Casella-Control-and-Modelica.pdf (page 20) My example is: a pump model producer pipe_flange w,k; parameter Real a,b

As stated above: I wish to compute the minimum (and/or maximum) of a continuous variable over time. Here is a minimal example to demonstrate: model MinMaxTest Real u; Real u_min(start = 10); Real u_max(start = -10); equation u = sin(time / 180 * Modelica.Constants.pi); u_min = min(u, u_min); u_max = max(u, u_max); annotation(experiment(StartTime = 0, StopTime = 360, Tolerance = 1e-06, Interval = 1)); end MinMaxTest; u is the arbitrary continuous variable (for demo purposes a simple sinus wave). u_min / u_max is the minimum/maximum over time. Obviously the expected result is u_min=-1 and u_max

I am trying to develop a simulation in OpenModelica of a flow that has a single substance that will be liquid or vapor. The Modelica.Media.Water models do have two phases, but are extremely complicated, and would be very hard to reproduce for a completely different substance. I would like to find a simple example of a two phase medium that I can work from. There is a partial package TemplateMedium and a partial package PartialTwoPhaseMedium, but I don't see any examples of how to write a completely new Medium that can be in either of two phase. If anyone can provide a simple example, or just a