Overview Levels of Dynamic System Simulation Fidelity Physical systems can be simulated at many levels of complexity. The"correct"level depends on the purpose of the simulation 1. Atomic level uses quantum mechanical partial differential equations(PDE's Purpose: molecular level effects Applications nuclear physics 2. Continuum (or distributed parameter)-uses field equations (PDE's Purpose: study quantities that vary significantly over the points in a geometric object Applications detailed aerodynamics, impact analysis, component (e.g. valve)analysis 3. Macroscopic (or lumped parameter)-uses ordinary differential equations Applications Flight controls, hydraulic system analysis, electric power system contro Purpose: study quantities that vary in time but can be averaged over spatial components 4. Systems analysis - uses algebraic equations with time delays Purpose: study quantities that effectively change value instantaneously at discrete instances of time Applications: Scheduling, communications Each level requires orders of magnitude more effort than the next highest but prov ides more accurate results MSC EASY5 is usually used to model dynamic systems at Level 3, but occasionally it is used for level 2 EAS102. December 2005 pyright@ 2005 MSC Software Corporation Chart 8EAS102, December 2005 Copyright© 2005 MSC.Software Corporation Chart 8 Physical systems can be simulated at many levels of complexity. The “correct” level depends on the purpose of the simulation. 1. Atomic level – uses quantum mechanical partial differential equations (PDE’s) – Purpose: molecular level effects – Applications: nuclear physics 2. Continuum (or distributed parameter) - uses field equations (PDE’s) – Purpose: study quantities that vary significantly over the points in a geometric object – Applications: detailed aerodynamics, impact analysis, component (e.g. valve) analysis 3. Macroscopic (or lumped parameter) - uses ordinary differential equations – Purpose: study quantities that vary in time but can be averaged over spatial components – Applications: Flight controls, hydraulic system analysis, electric power system control 4. Systems analysis - uses algebraic equations with time delays – Purpose: study quantities that effectively change value instantaneously at discrete instances of time – Applications: Scheduling, communications Each level requires orders of magnitude more effort than the next highest but provides more accurate results. MSC.EASY5 is usually used to model dynamic systems at Level 3, but occasionally it is used for Level 2. Levels of Dynamic System Simulation Fidelity Overview