A flux splitting scheme is proposed for the general nonequilibrium flow equations with an aim at removing numerical dissipation of Van-Leer-type flux-vector splittings on a contact discontinuity. The scheme obtained is also recognized as an improved Advection Upwind Splitting Method (AUSM) where a slight numerical overshoot immediately behind the shock is eliminated. The proposed scheme has favorable properties: high-resolution for contact discontinuities; conservation of enthalpy for steady flows; numerical efficiency; applicability to chemically reacting flows. In fact, for a single contact discontinuity, even if it is moving, this scheme gives the numerical flux of the exact solution of the Riemann problem. Various numerical experiments including that of a thermo-chemical nonequilibrium flow were performed, which indicate no oscillation and robustness of the scheme for shock/expansion waves. A cure for carbuncle phenomenon is discussed as well.

A Flux Splitting Scheme with High-Resolution and Robustness for Discontinuities(Proceedings of the 12th NAL Symposium on Aircraft Computational Aerodynamics)

This review surveys micromachined gyroscope structure and circuitry technology The principle of micromachined gyroscopes is first introduced Then, different kinds of MEMS gyroscope structures, materials and fabrication technologies are illustrated Micromachined gyroscopes are mainly categorized into micromachined vibrating gyroscopes (MVGs), piezoelectric vibrating gyroscopes (PVGs), surface acoustic wave (SAW) gyroscopes, bulk acoustic wave (BAW) gyroscopes, micromachined electrostatically suspended gyroscopes (MESGs), magnetically suspended gyroscopes (MSGs), micro fiber optic gyroscopes (MFOGs), micro fluid gyroscopes (MFGs), micro atom gyroscopes (MAGs), and special micromachined gyroscopes Next, the control electronics of micromachined gyroscopes are analyzed The control circuits are categorized into typical circuitry and special circuitry technologies The typical circuitry technologies include typical analog circuitry and digital circuitry, while the special circuitry consists of sigma delta, mode matching, temperature/quadrature compensation and novel special technologies Finally, the characteristics of various typical gyroscopes and their development tendency are discussed and investigated in detail

The Development of Micromachined Gyroscope Structure and Circuitry Technology

In an exposure apparatus of the invention, for a spatial light modulator, each of a plurality of pixel portions fewer than the total number of the pixel portions is controlled with a control signal generated according to exposure information. Namely, a part of the pixel portions is controlled without controlling a whole of the pixel portions on the substrate. Thus, the number of pixels in the pixel portions is decreased, and transfer time of the control signal becomes short. This enables modulation speed of the laser beam to be increased and the high-speed exposure to be performed. An incorporated laser light source, in which the laser beams are incorporated and struck on the optical fiber, is preferable to the laser device. By adopting the incorporated laser light source, high brightness and high output can be obtained, and it is preferable to the exposure of the spatial light modulator. Since the fiber array is obtained with few optical fibers, it is low cost. Since the number of optical fibers is few, the light-emitting region is further decreased when the optical fibers are arrayed.

Exposure head, exposure, apparatus, and application thereof

Vortex methods have a history as old as finite differences. They have since faced difficulties stemming from the numerical complexity of the Biot–Savart law, the inconvenience of adding viscous effects in a Lagrangian formulation, and the loss of accuracy due to Lagrangian distortion of the computational elements. The first two issues have been successfully addressed, respectively, by the application of the fast multipole method, and by a variety of viscous schemes which will be briefly reviewed in this article. The standard method to deal with the third problem is the use of remeshing schemes consisting of tensor product interpolation with high-order kernels. In this work, a numerical study of the errors due to remeshing has been performed, as well as of the errors implied in the discretization itself using vortex blobs. In addition, an alternative method of controlling Lagrangian distortion is proposed, based on ideas of radial basis function (RBF) interpolation (briefly reviewed here). This alternative is formulated grid-free, and is shown to be more accurate than standard remeshing. In addition to high-accuracy, RBF interpolation allows core size control, either for correcting the core spreading viscous scheme or for providing a variable resolution in the physical domain. This formulation will allow in theory the application of error estimates to produce a truly adaptive spatial refinement technique. Proof-of-concept is provided by calculations of the relaxation of a perturbed monopole to a tripole attractor.

/pdf/advances-in-viscous-vortex-methods-meshless-spatial-adaption-bou012v62m.pdf

Advances in viscous vortex methods - meshless spatial adaption based on radial basis function interpolation

This paper presents analytical modeling, 3-D electro-fluid–structural simulations, fabrication and test of a piezoelectrically actuated PDMS based planar valveless micropump. The analytical model considers force balance in the nozzle-diffuser elements and at the fluid–membrane interface to predict the natural frequency and flow rate performance of the proposed micropump. The numerical model employs two-way fluid–structure coupling to represent fluid–structure interaction (FSI) between the membrane and working fluid by mapping displacement data from the membrane to the fluid and force data from the fluid to the surface of the membrane. Also, electro-structure coupling between deformation of a piezoelectric disk due to an applied voltage and resulting displacement of the membrane is considered. Based on the simulations, the circular shape of the chamber used in conventional micropump designs is modified to include a taper at the outlet, which provides a significant improvement (∼28%) in the flow rate. Numerical simulations are performed to study the effects of the nozzle-diffuser angle and size, chamber diameter and height and membrane diameter and thickness on the flow rate. Using simulation results, a suitable design of the micropump is identified and the proposed micropump is fabricated. Experiments are performed to study the effect of frequency and voltage on the flow rate and pressure-flow characteristics. The predictions of the analytical model and numerical simulations in terms of flow rate versus frequency and voltage and pressure-flow characteristics compare well with the corresponding experimental data (within 20%). Using a peak-to-peak voltage of 30 V, the micropump delivers a maximum flow rate of 20 μL/min and back pressure of 220 Pa. The proposed micropump is polymer based and thus suitable for low-cost and disposable applications.

Analytical modeling, simulations and experimental studies of a PZT actuated planar valveless PDMS micropump

Viscous flow simulation using the discrete vortex model: the diffusion velocity method

PROBLEM TO BE SOLVED: To provide a means for efficiently mixing and agitating a sample liquid with a reagent liquid in microchemical analysis using a microanalysis chip. SOLUTION: This microanalysis chip 100 has inflow ports 2a, 2b for injecting the sample liquid and the reagent liquid, and an outflow port 3 for discharging a reaction liquid comprising the sample liquid and the reagent liquid recessed on the upper surface side of a flat rectangular plate, micro-flow passages 4 for flow of the sample liquid or the reagent liquid are provided to correspond to the respective inflow ports 2a, 2b to be combined with each other at a mixing part 10, and then introduced to the outflow port 3, and a light pressure mixer 20 rotated by driving force of light pressure generated by irradiation of light is disposed at the mixing part 10. COPYRIGHT: (C)2001,JPO

Microanalysis chip, and method of manufacturing the same

A simple fluid–diaphragm coupling model for studying the dynamic performance of valveless micropumps is presented. The model includes fluid inertia and a squeeze film effect by solving the coupling equation simultaneously with the Reynolds equation. The model is validated with a valveless diffuser micropump actuated by either a piezoelectric or electromagnetic diaphragm. The performance of the pump is considered for pumping liquid and air. The resonant frequency and dynamic performance of the micropumps obtained by the model are in good agreement with the experimental data. The model can predict well the damping behavior of the pump.

A dynamic model of valveless micropumps with a fluid damping effect

In this paper, a fluid–diaphragm coupling model is proposed for studying the dynamic performance of a valveless micropump. In the model, fluid inertia is included and fluid pressure is obtained by solving the coupling equation simultaneously with Navier–Stokes equations through a transient dynamic mesh simulation. This process avoids the omission of the phase shift between the pressure force on the diaphragm and the flow rate of the pump. Furthermore, in this model, empirical parameters are almost eliminated. The model was applied to study the dynamic performance of a valveless electromagnetic micropump which uses a new working principle. The obtained results show that the flow rate attains its maximum value for a range of driving frequency. For instance, the flow rate reaches 1.6 ml min−1 for frequencies of 26–30 Hz when the electromagnetic force is 20 mN. The simulation results demonstrate that the flow rate of the proposed pump is much larger than that of the diffuser pump counterpart. A MEMS prototype has been fabricated and the attained backpressure validates the new pumping principle of the pump.

A dynamic model for studying valveless electromagnetic micropumps

A new vortex scheme for simulating flows involving natural convection and interaction of temperature and vorticity is presented. The creation of vorticity from temperature is modeled either by creating a vortex pair from a temperature particle or by changing the strength of vortices according to the vorticity equation. The diusion velocity method is used for simulating the diusion of vorticity and temperature. The vortices of negative and positive strength are separately treated in diusion process to avoid an unreasonably large diusion velocity. Our results indicates that these techniques successfully simulate creation of vorticity from heat, diusion and convection of temperature and vorticity, and interaction of them.

/pdf/simulation-of-heat-vortex-interaction-by-the-diffusion-35tfslf92g.pdf

Yoshifumi Ogami

Papers

Viscous flow simulation using the discrete vortex model: the diffusion velocity method

Microanalysis chip, and method of manufacturing the same

A dynamic model of valveless micropumps with a fluid damping effect

A dynamic model for studying valveless electromagnetic micropumps

Simulation of heat-vortex interaction by the diffusion velocity method