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Simulink in barebones form not-well suited for simulating networks/nodal systems ◦ 1) No sense of bi-directionality ◦ 2) No notion of ‘nodes’ ◦ 3) Energy conservation has to be maintained via algebraic constraint blocks in each sub-unit Can be done….but very messy, difficult to expand Approach ◦ Solve network state in one custom block Pros ◦ Better understood on how to get the correct solution Cons ◦ Not well-suited for ‘group’ approach ◦ Code interface to solver block could get messy fast ◦ Hard to expand to new sub-systems Approach ◦ Use Simulink ‘Simscape’ Libraries Pros ◦ Let Simulink do the book-keeping for energy conservation, flows, network state, time etc ◦ Graphical components for building networks Cons ◦ Built-in Hydraulic domain assumes constant temperature ◦ New thermo/hydraulic domain (and accompanying components) have to be written/re-written A simulink package to model physical domains and networks Based off of ‘Bond-Graph’ Theory ◦ Physical dynamic systems can be abstracted into networks in which: 1) There exists “Flow” variables 2) There exists “Effort” variables 3) Energy is conserved How to write a domain that couples hydraulic and thermal behavior? ◦ Learn the mechanics of ‘Simscape’ Language (structure, syntax, etc) ◦ Test with a sample, energy conserving networks How to modify that domain to accurately model our system? ◦ Mass flow rate, pressure, enthalpy, momentum, etc. ◦ Build a source, flowing into a simple network of pipes Electro-Hydraulic Servo valve Example 2 ‘Effort’ (across) variables ◦ Temperature and Pressure drops 2 Corresponding ‘FLOW’ variables Power = Flow*Effort ◦ Energy conserving variables noted ◦ Default values assigned (but are over-written in each model) At,p + qf qt Bt,p Component Template Constraints, not assignments! Includes both domains, but not coupled Units matter!! Reference node What are our effort variables and units? What are our flow variables and units? What are the governing network equations, in nodal form? What are the domain coupling expressions/constraints between the two domains?