Search results for "Simulation."
showing 10 items of 4779 documents
Numerical simulations of the dependency of flow pattern on impeller clearance in stirred vessels
2001
The flow and turbulence fields in a fully baffled vessel stirred by a Rushton turbine have been simulated by means of computational fluid dynamics (CFD) techniques. The simulation techniques adopted (the "Sliding-grid" and "Inner-outer" methods) are fully predictive and require no experimental data as boundary or initial conditions. The effect of clearance (C) on the flow patterns in stirred vessels was simulated as the flow field transition observed can be considered a particularly stringent benchmark for the testing of CFD techniques. The results are compared with previously obtained LDA data and show that the double- to single-loop transition experimentally observed when impeller clearan…
Experimental investigation of Brillouin and Raman scattering in a 2SG sulfide glass microstructured chalcogenide fiber.
2008
International audience; In this work, we investigate the Brillouin and Raman scattering properties of a Ge15Sb20S65 chalcogenide glass microstructured single mode fiber around 1.55 microm. Through a fair comparison between a 2-m long chalcogenide fiber and a 7.9-km long classical single mode silica fiber, we have found a Brillouin and Raman gain coefficients 100 and 180 larger than fused silica, respectively.
Crystal shape 2D modeling for transient CZ silicon crystal growth
2013
Abstract A non-stationary axisymmetric model of Czochralski silicon single crystal growth is presented. The model describes transient behavior of crystal–melt, melt–gas and crystal–gas interfaces in connection with PID-based control of crystal diameter by changing crystal pulling velocity and heater power. To calculate significant crystal shape changes, unstructured finite element mesh is used in crystal and melt together with automatic element size control. Heater temperature changes are modeled with a simplified integral model. A numerical simulation example of start cone growth is given.
Evaluation of the Performance of Published Point Defect Parameter Sets in Cone and Body Phase of a 300 mm Czochralski Silicon Crystal
2021
Prediction and adjustment of point defect (vacancies and self-interstitials) distribution in silicon crystals is of utmost importance for microelectronic applications. The simulation of growth processes is widely applied for process development and quite a few different sets of point defect parameters have been proposed. In this paper the transient temperature, thermal stress and point defect distributions are simulated for 300 mm Czochralski growth of the whole crystal including cone and cylindrical growth phases. Simulations with 12 different published point defect parameter sets are compared to the experimentally measured interstitial–vacancy boundary. The results are evaluated for stand…
Steady State Counterbalance Valve Modeling with the Influence of Synthetic Ester Oils Using CFD
2020
This study looks in details at the effects of synthetic esters being applied to a counterbalance valve from the perspective of a system engineer. There is limited literature on the subject of applied synthetic esters and as such limited unbiased sources for information. This creates reluctance against the use of these fluids in sectors and regions with no prior experience and knowledge of what to expect. This study expands the applied literature by investigating a commercially available valve using commercial oils, a basic synthetic ester, a fully saturated synthetic ester and a typical mineral oil type for benchmarking. The investigation is based on both computational fluid dynamics and ex…
Experiments and CFD Predictions of Solid Particle Distribution in a Vessel Agitated with Four Pitched Blade Turbines
2001
The distribution of solid particles in a high aspect-ratio baffled tank agitated with four 45° pitched blade turbines (PBT) was investigated using both experimental measurements and CFD simulations. Dilute suspensions of glass beads in water and moderately viscous liquids were considered. The measurement of axial particle concentration profiles was conducted by means of a light attenuation technique. Fully predictive simulations of solid-liquid suspensions were performed using a Sliding-Grid approach coupled with the Eulerian-Eulerian Two Fluid Model and the ‘homogeneous’ two-phase k-ɛ turbulence model. The simulated particle axial concentration profiles were compared with the experimental …
Calculation of the elastic–plastic strain energy density under cyclic and random loading
2001
Abstract The paper presents a method of identification and calculation of the components of strain energy density under cyclic and random loading causing elastic–plastic strain in the material. The method consists in integration of the history of the strain instantaneous power.
Empirical model for stress ratio effect on fatigue delamination growth rate in composite laminates
2004
An empirical model is proposed for the stress ratio effect on the fatigue delamination growth rate in composite laminates under single-mode loading, intending to provide a simple and accurate description tool in engineering application. The model is based on heuristic considerations of damage accumulation ahead of the crack. Linear cumulative assumption is used for damage estimation. Comparison of the prediction based on the proposed model with the test results for different carbon, glass, and alumina fibre-reinforced composites at several stress ratios shows reasonable agreement.
A simulation and experimental study of electrochemical pH control at gold interdigitated electrode arrays
2021
Abstract In electroanalysis, solution pH is a critical parameter that often needs to be tailored and controlled for the detection of particular analytes. This is most commonly performed by the addition of chemicals, such as strong acids or bases. Electrochemical in-situ pH control offers the possibility for the local adjustment of pH at the point of detection, without the need for additional reagents. Finite element analysis (FEA) simulations have been performed on interdigitated electrodes, to guide experimental design in relation to both electroanalysis and in-situ control of solution pH. No previous model exists that describes the generation of protons at an interdigitated electrode arra…
Interfacial energy effects within the framework of strain gradient plasticity
2009
AbstractIn the framework of strain gradient plasticity, a solid body with boundary surface playing the role of a dissipative boundary layer endowed with surface tension and surface energy, is addressed. Using the so-called residual-based gradient plasticity theory, the state equations and the higher order boundary conditions are derived quite naturally for both the bulk material and the boundary layer. A phenomenological constitutive model is envisioned, in which the bulk material and the boundary layer obey (rate independent associative) coupled plasticity evolution laws, with kinematic hardening laws of differential nature for the bulk material, but of nondifferential nature for the layer…