ASEN5519 Topics in Multiphysics Modeling

Transcription

1 ASEN5519 Topics in Multiphysics Modeling Lecture01: Introduction Class of Coupled-Field Problems Coupling/Interface Classification Some Challenging Problems Modeling and Analysis Challenges

2 Why do we want to study coupled-field problems? Single-discipline oriented traditional science and engineering education curricula are proving to be less effective (exceptions do exist!), because adequate solutions of modern science and engineering problems do require interdisciplinary approaches. Coupled-field problems is just one approach to address interdisciplinary challenges. Mechanical, aerospace and civil engineering systems involve judicious integrations of: structural/solid mechanics, fluid/gas/air dynamics, control, acoustics, electrodynamics, thermal fields, material processing, etc.

3 Why do we want to study coupled-field problems? cont d Most important of all, we do want to utilize all the existing design, modeling and analysis software modules that have been developed for single field problems (structural analysis software, fluid flow software, electrodynamics software, thermal analysis software modules) to tackle coupled-field problems without having to reinvent new design and analysis software for interaction problems! Hence, the modeling and analysis paradigm has to be partitioned modeling and analysis on which much of this course is focused.

4 Class of Coupled-Field Problems Structure-structure interaction: beam-plate, solid-plate, solid-bar, nano-micro-meso-continuum, fuselagewing-stabilizer, body-floor-engine blocks, etc. Structure-fluid interaction: (wing, propeller, rotor blade)-fluid, vane-blood flow, heart-hemodynamics, (surface ship, submerged vehicle, ocean drilling platform, underwater telephone cable)-ocean waves and currents,... Structure-thermal interaction: satellite structure-solar radiation, turbine blade-hot wter/gas flow, metal forming. Structure-control/acoustic interaction: vibration mitigation, noise mitigation, sound generation, acoustic sensors, pressure sensors, etc.

5 Class of Coupled-Field Problems cont d Structure-electrodynamic interaction: MEMS devices such as resonators, gyroscope, sensors of all categories, magnetically levitated vehicle, motor rotors,... Multi-scale interaction: molecule-molecules, nano-micro, micro-continuum,... Fluid-thermal interaction: large circulation of ocean currents, upper-lower atmospheric dynamics, geophysics of several length scales,...

6 Coupling/Interface Classification Integration of field variables at the interfaces non-overlapping interfacing. overlapping interfacing. Classical (or global) Lagranges multiplier method Localized Lagranges multiplier method Matched impedance interface Reduced (or filtered) interface models

7 Some Challenging Problems Structural mechanics problems consisting of subsystems that exhibit from discontinuity, rapidly varying spatial and temporal characteristics, medium frequencies, and slowly varying subsystems. Multiphysics problems that utilize single-field simulation capabilities of differing time and spatial resolution requirements. Multiscale problems that needs model refinements whose grid sizes vary several orders of magnitude from finer grids to coarse grid zones.

8 Modeling and Analysis Challenges How to construct interactions How best to preserve software modularity of single-field analyzers How to capture the interaction phenomena without overburdening the task of modeling of the interfaces How to capture the essential physical insight with a minimum of model orders

9 Let s get down to the business, that is, formulating the coupled-field problems via partitioned formulation. What is partitioned formulation? It is a divide-and-conquer strategy in modeling complex systems by the following procedure: Construct the total energy of completely free system for each of the constituent single-field systems. Here, the term energy is broadly used to encompass the total energy, the total Lagrangian, the total Hamiltonian, etc. Construct the interface mechanisms in terms of constraints and obtain the constraint functional via the method of Lagrange multipliers. Add the all the energy of the constituent single fields to form the total system energy.

10 What is partitioned formulation? - - cont d Append the constraint functional to the total system energy. Perform discretization while adhering to the single field-specific discretization for each field. Perform the variational process when applicable, or perform a weak-form leastsquares discretization. Develop solution procedures or design optimization procedures that preserves single-field analysis and design software modules. Acquire physical insight through the analysis of coupled-field problems and apply it for improved and/or new products.