Visual numerical simulations

VISUAL NUMERICAL SIMULATION OF COUPLED GAS LEAK FLOW AND COAL-ROCK DEFORMATION IN PARALLEL COAL SEAMS... 

Multiscale modeling is an approach to minimize system-dependent empirical correlations for drag, particle-particle, and particle-fluid interactions [19]. This approach is visualized in Eigure 15.6. A detailed model is developed on the smallest scale. Direct numerical simulation (DNS) is done on a system containing a few hundred particles. This system is sufficient for developing models for particle-particle and particle-fluid interactions. Here, the grid is much smaller... 

So far, some researchers have analyzed particle fluidization behaviors in a RFB, however, they have not well studied yet, since particle fluidization behaviors are very complicated. In this study, fundamental particle fluidization behaviors of Geldart s group B particle in a RFB were numerically analyzed by using a Discrete Element Method (DEM)- Computational Fluid Dynamics (CFD) coupling model [3]. First of all, visualization of particle fluidization behaviors in a RFB was conducted. Relationship between bed pressure drop and gas velocity was also investigated by the numerical simulation. In addition, fluctuations of bed pressure drop and particle mixing behaviors of radial direction were numerically analyzed. 

Kiya, M., K. Toyoda, H. Ishii, M. Kitamura, and T. Ohe. 1992. Numerical simulation and flow visualization experiment on deformation of pseudo-elliptic vortex rings. Fluid Dyn. Res. 10 117-31. 

The focused laser beam is scanned along an arbitrary path within the xy-plane as sketched in Fig. 10. The perspective view with the cross section through the scan path shown in Fig. 10a visualizes the color-coded concentration change due to the Soret effect according to the numerical simulation discussed later on. On the right hand side a phase contrast micrograph is shown where the word Soret has been written into the polymer blend. 

The operation of the numerical model will be illustrated by means of three computer experiments, chosen more for their value in visualizing reactive flow than as detailed numerical simulations of real industrial processes. Simple fluid property models will be used in which material parameters such as viscosity and reaction order are not allowed to vary during the process, although real situations are often much more complicated than this. The numerical model does have the capability of performing... 

M. Bak, R. Schultz, T. Vosegaard and N. C. Nielsen, Specihcation and visualization of anisotropic interaction tensors in polypeptides and numerical simulations in biological solid-state NMR. J. Magn. Reson., 2002, 154, 28-45. 

As in other application areas that examine flow phenomena, in plastics processing numerical simulations replace the common model-based experiment. With increasing complexity, the requirements on the methods for the visualization rise. Traditionally, visualization software allows the simple animation of transient data sets. This is not enough for the interactive exploration of complex flow phenomena, which is, in contrast to a confirmative analysis, comparable to an undirected search in the visualization parameters for a maximum insight into the simulation. In a worst case scenario, important features of a flow are not detected. Due to this fact, the interactive explorative analysis in a real-time virtual environment is demanded by scientists. 

Current investigations are directed toward full-field measurement techniques and direct numerical simulation (DNS). The numerical approaches are limited by the need for much bigger and better computers. Previously, visual observations were used for qualitative assessment. Hot-wire/film and LDA measurements were used to provide the hard numbers for a few points in space in the time domain. Today, the visual-based techniques are being extended to allow full-field, time-resolved velocity vector information to be obtained. However, the need for full-field and time-resolved measurements put vast restrictions on what can be accomplished. To get time-resolved results, often today, we must sacrifice resolution. To get resolution, we must sacrifice the dynamics. Ultimately we want both. 

ABSTRACT In order to investigate the effect of coal particle size on gas desorption and diffusion law at constant temperature, the constant temperature dynamic coal particle gas adsorption and desorption experiment with different particle sizes was conducted in the coal gas adsorption and desorption experiment system. The results suggest that gas desorption laws of different particle size of coal samples show a good consistency at different pressures, and the cumulative desorption of gas coal particle is linear with time. For the same particle, the higher the initial pressure, the more the maximum gas desorption the smaller the coal particle is, the more quickly the gas desorption rate is at the same initial pressure. Then, the gas spherical flow mathematical model is built based on Darcy law and is analysed with finite difference method. At last, the gas spherical flow mathematical model is constructed with Visual Basic. The contrast between numerical simulation and experimental results shows that the gas flow in the coal particle internal micropore accords with Darcy s law. 

The time dependent solvation funetion S(t) is a directly observed quantity as well as a convenient tool for numerical simulation studies. The corresponding linear response approximation C(t) is also easily eomputed from numerical simulations, and can also be studied using suitable theoretical models. Computer simulations are very valuable both in exploring the validity of such theoretical calculations, as well as the validity of linear response theory itself (by comparing S(t) to C(t)). Furthermore they can be used for direct visualization of the solute and solvent motions that dominate the solvation process. Many such simulations were published in the past decade, using different models for solvents such as water, alcohols and acetonitrile. Two remarkable outcomes of these studies are first, the close qualitative similarity between the time evolution of solvation in different simple solvents, and second, the marked deviation from the simple exponential relaxation predicted by the Debye relaxation model (cf Eq. [4.3.18]). At least two distinct relaxation modes are... 

Microscale flow visualization has played a key role in the development of the microfluidics and LOC fields. It is central to fundamental understanding of microflows, developing novel microfluidic processes, investigating nonideal and nonlinear behaviors, and providing data for numerical simulations. Many microfluidic applications such as mixing, pumping, and filtering require flow visualization to characterize device efficiency. To date, most microscale flow... 

Even if the flow conditions of liquids on the microscale are almost laminar and therefore numerical simulations with high accuracy are applicable, there are several reasons for the basic necessity for experimental flow visualization. In most cases, for instance, the exact data of geometries and wall conditions of microchannels and data on chemical media such as diffusion coefficients and reaction rates are unknown. Furthermore, in cases of chemical reactions, the interaction between mass transport and conversion are not calculable to date, especially if simultaneous catalytic processes take place. Therefore, the visualization of microscale flow is a helpful tool for understanding and optimizing microchannels. 

In order to visualize the reaction-diffusion process of a second-order reaction in a T-shaped micromixer, Baroud et cd. used the reaction between Ca and CaGreen, a fluorescent tracer for calcium. The experimental measurements were compared with the 2D numerical simulation of the reaction-diffusion equations and showed good agreement between theory and experiment. From this study, it is possible to extract... 

Microscale flow visualization has become an important tool for characterizing the performance of microchannels, micromixers and microreactors. Due to the rapid improvement in computer power and the great efforts in optical instrumentation, new measuring systems with high spatial and temporal resolution are available even for smaller companies and research institutes. In connection with the recent success in numerical simulation of microscale flow, a signiflcant acceleration in clariflcation of microscale phenomena and technical development can be expected. By ensuring the development of reliable systems, microscale flow visualization will provide an important contribution to the further spread of micro process engineering applications in the chemical and biochemical industries. 

Based on DMU, FDMU shall comprise the results of aU simulations needed for full presentation of the behavioral system description. Literally spoken, FDMU extracts the data from aU virtual models of a product and gives them a physical meaning. It makes the product function experienceable and facilitates the physicalisation of data by setting the physical effects in context of a product [27]. As a prerequisite, one has to ensure a deep interaction between visualization and numerical simulation with respect to product life-cycle management. FDMU application requires three basic components a description of the geometry, a description of the behavior and a comprehensive visualization of the results with fine adjustable filtering capability (Fig. 13.7). 

The application of Visual Modflow in groundwater numerical simulation is of high reliability and visualization. The simulation can reflect hydrogeologic situation in a real way, it can be used in groimdwater simulation. 

Xu L., Chen S.J., Xiang X.F., Zhang H. 2008. Honghu stone pier -Xiaogang section of groundwater numerical simulation based on Visual Modflow. Central China Normal University (2) 299-303... 

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