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This paper presents a framework for modeling essentially 1D devices and components embedded in multi-dimensional spaces. The main characteristic and main advantage of the new methodology is that the 1D and multi-dimensional objects or domain are meshed completely independently of each other, without regard to their relative alignment or location, a...
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... 1) fluid mechanics equations with convection, diffusion, electromigration of mixtures, electrolytes, and biomolecules [12][13][14]; 2) energy equation with conjugate heat transfer in solids, liquids and multiphase flows [15]; 3) general multistep chemical kinetics handling stiff reaction mechanisms [16]; 4) finite element method stress/deformation and dynamic model [17]; 5) electrostatics, electrodynamics, electromagnetics, and solid state electronics; 6) generalized electrokinetics of ionic mixtures for electrophoresis, electroosmosis and bioelectrochemistry [18]; 7) free surface flows in 3D using VOF method with surface tension and Marangoni effects for hydrophobic, hydrophilic liquid filling and microdispensing, liquid wicking in membranes and microcapillaries; 8) multiphase flows solved with Eulerian-Eulerian or Eulerian-Lagrangian method to simulate particle, bubble, droplet, micromolecule transport in microchannels; 9) surface chemistry to simulate competitive multi-protein binding, antigen-antibody, receptor-ligand, enzymesubstrate interactions, and non-specific multi-species binding [19]; and 10) mixed-level simulation capability in which 3D device model is connected to circuit models of the remaining parts of the entire microsystem -a link between CFD-ACE+ and SABER is used. ...
Advances in MEMS sensors for diversified applications require use of computational modeling and simulation accompanied by physical measurements. We believe that successful combination of computer aided design (CAD) and multiphysics simulation tools with a state-of-the-art (SOTA) measurement methodology will contribute to reduction of high prototyping costs, long product development cycles, and time-to-market pressures while developing MEMS for a variety of applications. In our approach we combine a unique, fully integrated, software environment for multiscale, multiphysics, high fidelity modeling of MEMS with the SOTA optoelectronic laser interferometric microscope (OELIM) methodology for measurements. The OELIM methodology allows remote, noninvasive, full-field-of-view (FFV) measurements of displacements/deformations with high spatial resolution, nanometer accuracy, and in near real-time. In this paper, both, the modeling environment (including an analytical model used to quantitatively show an influence that various parameters defining a sensor may have on its dynamics -using this model dynamic characteristics of a sensor can be optimized by constraining its nominal dimensions and finding the optimum set of uncertainties/tolerances in these dimensions) and the OELIM methodology are described and their applications are illustrated with representative examples demonstrating viability of the approach, combining measurements and modeling (i.e., M&M), for development of MEMS. Preliminary results demonstrate capability of our M&M approach to quantitatively determine effects of dynamic operational loads on performance of selected MEMS.
... 1) fluid mechanics equations with convection, diffusion, electromigration of mixtures, electrolytes, and biomolecules [4][5][6]; 2) energy equation with conjugate heat transfer in solids, liquids and multiphase flows [7]; 3) general multi-step chemical kinetics handling stiff reaction mechanisms [8]; 4) finite element method stress/deformation and dynamic model [9]; 5) electrostatics, electrodynamics, electromagnetics, and solid state electronics; 6) generalized electrokinetics of ionic mixtures for electrophoresis, electroosmosis, and bioelectrochemistry [10]; 7) free surface flows in 3D using VOF method with surface tension and Marangoni effects for hydrophobic, hydrophilic liquid filling and microdispensing, liquid wicking in membranes and microcapillaries; 8) multiphase flows solved with Eulerian-Eulerian or Eulerian-Lagrangian method to simulate particle, bubble, droplet, micromolecule transport in microchannels; 9) surface chemistry to simulate competitive multi-protein binding, antigen-antibody, receptor-ligand, enzyme-substrate interactions, and non-specific multi-species binding [11]; and 10) mixed-level simulation capability in which 3D device model is connected to circuit models of the remaining parts of the entire microsystem -a link between CFD-ACE+ and SABER is used. ...
Microelectromechanical systems (MEMS), also called microsystems, hold a promise to dramatically influence the consumer, industrial, medical, and defense markets. It is generally recognized that the microsystems technology will lead to advancement of MEMS-based products that will drive these markets. MEMS chips are being developed to host mechanical devices, bioanalytical devices, photonic devices, and myriad of others, all integrated with electronics. It is generally believed that success in development of these chips, to a large extent, will be determined by availability of computer aided design (CAD) and multiscale multiphysics simulation tools for MEMS. This paper presents a unique, fully integrated, software environment for multiscale, multiphysics, high-fidelity analysis of MEMS. The multiphysics simulations allow for a streamlined parametric analysis of coupled multidisciplinary effects, while multiscale simulations allow for full analysis of the entire device as well as detailed analysis of specific components of a given device. The paper discusses overall software architecture, geometry/meshing approach, some of the multiphysics field solvers, and multidisciplinary coupling procedures. These discussions are illustrated with representative examples.
Advances in MEMS, also called microsystems, require the use of computational modeling and simulation with physical measurements, i.e., measurements and modeling (M&M) approach is needed. We believe that successful combination of computer aided design (CAD) and multiphysics/ multiscale simulation tools with the state-of-the-art (SOTA) measurement methodology will contribute to reduction of high prototyping costs, minimization of long product development cycles as well as time-to-market pressures while developing MEMS for various applications. In our approach we combine a unique, fully integrated, software environment for multiscale, multiphysics, high fidelity analyses of MEMS with the SOTA optoelectronic laser interferometric microscope (OELIM) methodology. The OELIM methodology allows remote, noninvasive, full-field-of-view measurements of deformations with very high spatial resolution, nanometer accuracy, and in near real-time. In this paper, both, the software environment and the OELIM methodology are described and their applications are illustrated with representative results demonstrating viability of the M&M approach to the development of MEMS. These preliminary results demonstrate capability of the M&M approach to quantitatively determine effects that static and dynamic loads have on the performance of MEMS.
Comprehensive assessment of the toxic physiological effects of short and long term exposure to nanoparticles requires a detailed understanding of particle deposition and partitioning within the body (the "dose"), and the inflammatory cellular "response" to the dose. In this paper, we report on the progress towards the development of an integrated computational architecture for the assessment of nanoparticle toxicity. The simulational methodology uniquely couples mixed-dimensional spatio-temporal models of nanoparticle dispersion with quantitative, dynamic models of cellular response. Critical elements of the modeling framework are demonstrated for nanoparticle inhalation via the pulmonary route. Results for aerosol deposition and dispersion in fully 3D models derived from medical imaging data as well as 1D model of stochastically generated tracheobronchial tree are presented. At the cellular level, particle chemical properties are used to yield predictions of the dynamic cellular - oxidative, inflammatory and apoptotic - response to the received dose.
We describe results of numerical simulations of steady flows in tubes with branch bifurcations using fully 3D and reduced 1D geometries. The intent is to delineate the range of validity of reduced models used for simulations of flows in microcapillary networks, as a function of the flow Reynolds number Re. Results from model problems indicate that for Re less than 1 and possibly as high as 10, vasculatures may be represented by strictly 1D Poiseuille flow geometries with flow variation in the axial dimensions only. In that range flow rate predictions in the different branches generated by 1D and 3D models differ by a constant factor, independent of Re. When the cross-sectional areas of the branches are constant these differences are generally small and appear to stem from an uncertainty of how the individual branch lengths are defined. This uncertainty can be accounted for by a simple geometrical correction. For non-constant cross-sections the differences can be much more significant. If additional corrections for the presence of branch junctions and flow area variations are not taken into account in 1D models of complex vasculatures, the resultant flow predictions should be interpreted with caution.
We describe a novel Convected Element Method (CEM) for simulation of formation of functional blood vessels induced by tumor-generated growth factors in a process called angiogenesis. Angiogenesis is typically modeled by a convection-diffusion-reaction equation defined on a continuous domain. A difficulty arises when a continuum approach is used to represent the formation of discrete blood vessel structures. CEM solves this difficulty by using a hybrid continuous/discrete solution method allowing lattice-free tracking of blood vessel tips that trace out paths that subsequently are used to define compact vessel elements. In contrast to more conventional angiogenesis modeling, the new branches form evolving grids that are capable of simulating transport of biological and chemical factors such as nutrition and anti-angiogenic agents. The method is demonstrated on expository vessel growth and tumor response simulations for a selected set of conditions, and include effects of nutrient delivery and inhibition of vessel branching. Initial results show that CEM can predict qualitatively the development of biologically reasonable and fully functional vascular structures. Research is being carried out to generalize the approach which will allow quantitative predictions.
Advances in MEMS inertial sensors, such as gyroscopes, require the use of computational modeling and simulation with physical measurements. We believe that successful combination of computer aided design (CAD) and multiphysics simulation tools with the state-of-the-art (SOTA) measurement methodology will contribute to reduction of high prototyping costs, long product development cycles, and time-to-market pressures while developing MEMS gyroscopes for various military and commercial applications. In our approach we combine a unique, fully integrated, software environment for multiscale, multiphysics, high fidelity analyses of MEMS gyroscopes with the SOTA optoelectronic laser interferometric microscope (OELIM) methodology. The OELIM methodology allows remote, noninvasive, full-field-of-view measurements of deformations with high spatial resolution, nanometer accuracy, and in near real-time. In this paper, both, the software environment and the OELIM methodology are described and their applications are illustrated with representative examples demonstrating viability of the hybrid approach, combining modeling and measurements, for the development of MEMS gyroscopes. These preliminary examples demonstrate capability of our approach to quantitatively determine effects of static and dynamic loads on the performance of MEMS gyroscopes.
