Title : Visualization of vortical particle-laden flows



Project Lead : Konstantin Volkov From : Kingston University (United Kingdom)

Dates : from 2014-09-02 21:43:12 to 2014-10-09 10:13:52

Description :

Motivation and objectives :
There has been a significant drop in the cost per unit of computing power and storage. This has led to a large increase in the size and computational complexity of computational fluid dynamics (CFD) computations resulting in the production of a large volume of computational data. Flow visualization is one of the most demanding problem areas in CFD. It allows the visualization not only of flow velocities, pressure and temperature distributions, but also transfer of heat, phase changes, physical movement induced by flow and areas of particle and droplet transport. The CFD visualization has applications in mechanical, automotive and aerospace engineering including energy systems, coating technology, fire safety through the modeling and simulation of turbulent transport and dynamics of particles. To fully understand the flowfield and to extract all flow phenomena hidden in the dataset it is post-processed and visualized. The simplest post-processing tools are widely used, and they are available in the most CFD packages. More advanced post-processing methods include the location of vortex cores, shock waves and surfaces in transonic flow, regions of large velocity gradients, fluctuations of flow parameters etc. The visualization of complex unsteady three-dimensional data fields is still a major research challenge. Choice of physical quantities (flow variable vectors, invariants of stress tensor and rotation tensor, Q-criteria etc) as well as visualization tools (streamlines, vector fields, level lines, cutting planes, particle trajectories etc) is case-dependent. The project aims to improve techniques of visualization of large CFD data and to develop a novel linkage between the CFD software tools and lighting simulation software in the visualization of turbulent compressible flows, and trajectories of liquid droplets or solid particles suspended in fluid or gas. CFD is used to predict the distributions of flow variables and distribution of particles, which are then processed and passed to the visualization tools. The specific objectives of the project are as follows: 1. To gain insight into about the influence of main parameters in the flow pattern and to validate the flow pattern predictions of a detailed CFD model. 2. To demonstrate the importance of using an accurate CFD model based on large-eddy simulation (LES) and direct numerical simulation (DNS) techniques in order to visualize the flow pattern. 3. To provide a better understanding of flow physics and turbulence flowfield in complex compressible turbulence flows including coherent and vertical structures, shock waves, regions with increased particle concentrations.

Teams :
The Centre for Fire and Explosion Studies (CFES) aims to deliver the highest quality research, postgraduate training and consultancy services in fluid dynamics, multi-phase modeling and simulation, fire and explosion modeling as well as environmental flows. The Centre is internationally renowned for its modeling capabilities based on computational fluid dynamics (CFD) techniques with a primary focus on large eddy and direct numerical simulations (LES and DNS) and other CFD calculations for problems involving large domain.

Dates :
starting date : 16 September, 2014
ending date : 20 September, 2014

Facilities descriptions :
http://visionair-browser.g-scop.grenoble-inp.fr/visionair/Browser/Catalogs/HLRS.GE.html

Recordings & Results :
A small set of computational data obtained on a coarse mesh was prepared and used for visualization. COVISE environment was used to visualize the data computed. Pictures based on different vortex criteria and video were generated. The visit was used for training purposes (COVISE software developed in HLRS, COVE). COVISE routine was generated that is suitable for visualization of data computed with in-house CFD code. The main results are a better understanding of flow physics and turbulence flowfield in complex compressible turbulence flows including coherent and vertical structures.

Conclusions :
The project focuses on CFD visualization of the results of direct numerical simulation and large eddy simulation of single and multi-phase flows in ducts, nozzles and jets. The results allow understanding the complex flow phenomena that exist in real flows, providing convincing illustration of the flow physics, minimizing the time and effort needed to describe the flow of interest. The methods developed use realistic volumetric gas rendering techniques to produce photo-realistic images and animations from scalar CFD data which are close to experimental pictures.




Project Images :

194_KonstantinVolkov.jpg




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VISIONAIR / Grenoble INP / 46 avenue Felix Viallet / F-38 031 Grenoble cedex 1 / FRANCE
Project funded by the European Commission under grant agreement 262044