Hi Ali, try fixed=true, this means the start value is not only a guess value.
partial class PneumoOneTerm Fitting fitting; Real p(fixed=true), G; equation p = fitting.p; G = fitting.G; end PneumoOneTerm; "time","volume.p", 0,100000.0014330081, 0.002,101612.6989615345, 0.004,103225.4216372393, 0.006,104838.1579805062, 0.008,106450.8726136756, Mit freundlichen Grüßen, Kind regards, Jens Frenkel _________________________________________________________________ Dipl.-Ing. Jens Frenkel ***************************************************************** Technische Universität Dresden Institut für Verarbeitungsmaschinen und Mobile Arbeitsmaschinen D-01062 Dresden Tel: 0351 463-39278 Fax: 0351 463-37731 E-Mail: [email protected] Internet: http://tu-dresden.de/bft Wissensportal: www.baumaschine.de ***************************************************************** ***************************************************************** Dresden University of Technology Institute of Processing Machines and Mobile Machinery D-01062 Dresden Germany Tel: +49 351 463-39278 Fax: +49 351 463-37731 E-Mail: [email protected] Internet: http://tu-dresden.de/bft ***************************************************************** Am 28.01.2012 17:26, schrieb Adrian Pop:
Hi all, Forwarding email from Ali. Ali, i now added you to OpenModelicaInterest as something went wrong with your subscription email. Cheers, Adrian Pop/ From: Ali Tlisov <[email protected]> Date: Sat, 28 Jan 2012 18:43:58 +0400 Subject: setting of initial values for variables have no effect To: [email protected] Hi! I'm new to modelica and openmodelica in particular but being impressed about it's capabilities and about physical modeling concept decided to try it. So maybe my question is stupid one anyway all suggestions are highly appreciated! I've tried to build simple model of Volume being filled by Gas through an Orifice. I try to set initial value of pressure in Volume (p.start = 1e5) but after simulating I see that it starts from zero in spite of my directions. Thank you for any help in advance! My code is as follows: connector Fitting flow Real G "Mass Flow"; Real p "Pressure"; end Fitting; partial class PneumoTwoTerm Fitting fin, fout; Real G; equation 0 = fin.G + fout.G; G = fin.G; end PneumoTwoTerm; partial class PneumoOneTerm Fitting fitting; Real p, G; equation p = fitting.p; G = fitting.G; end PneumoOneTerm; model PneumoSource extends PneumoOneTerm; end PneumoSource; model Orifice extends PneumoTwoTerm; input Real size; constant Real M = 29e-3; constant Real k = 1.4; constant Real R = 8.31441; parameter Real T = 273; algorithm G := fin.p * size * sqrt(M / (R * T)) * (2 / (k + 1)) ^ (1 / (k-1)) * sqrt(2 * k / (k + 1)); end Orifice; model VariableVolume extends PneumoOneTerm; input Real dV "Volume change"; Real Q "Energy given to system with incoming Gas"; Real L "Work of Gas"; Real U "Inner Energy of Gas"; Real V "Volume"; Real thetta "Amount of substance in Volume"; Real T(start = 273) "Temperature of Gas in volume"; parameter Real T_in = 273 "Temperature of incoming Gas"; constant Real c_V = 717, c_p = 1006; constant Real M = 29e-3 "Molar Mass of air"; constant Real k = 1.4 "Adiabate characteristic"; constant Real R = 8.31441 "Gas constant"; equation der(Q) = der(U) + der(L); der(L) = p * der(V); der(U) = c_V * der(thetta * T); der(Q) = c_p * T_in * der(thetta); der(V) = dV; der(thetta) * M = G; thetta * T = p * V / R; // Ideal Gas equation end VariableVolume; model Actuator PneumoSource source; Orifice orifice; VariableVolume volume(p.start = 1e5, V.start = 1e-2); equation connect(source.fitting, orifice.fin); connect(orifice.fout, volume.fitting); volume.dV = 0; orifice.size = 1e-4; source.p = 3e5; end Actuator;
