Block-Coupled Solution of Species and Energy Transport for Reacting Flows
Henrik Rusche1, Hrvoje Jasak2, Bastian Werdelmann3, Michael Huth3
1Wikki GmbH, Germany; 2Wikki Ltd., United Kingdom; 3Siemens AG, Germany
Detailed chemistry in FOAM can take up a substantial amount of time in the
solution process. A potential avenue to accelerate the time to solution is to
solve the species and energy equations together in a block-coupled manner. The
work follows the spirit of the work of Di Domenico, while the required
sensitivities (Jacobian) of the chemical sources terms are obtained by numerical
differentiation. The block-coupled species and energy transport has then been
implemented into two solvers: a laminar flame solver and an artificially
thickened flame solvers. The solvers have been validated for 1D test cases as
well as a complex 3D validation case.
This presentation covers an outline of the implementation, validation results
as well as performance comparisons for different time steps.
Massimiliano Di Domenico: Numerical Simulations of Soot Formation in Turbulent
Flows. PhD Thesis Universität Stuttgart, VT-Forschungsbericht 2008-01
Performance assessment of OpenFOAM on tip leakage flow inside a linear cascade under the design condition.
Dong-Kyung Sohn1, Gong-Hee Lee2,3
1Dept. of Reactor System Evaluation, Korea Institute of Nuclear Safety, Korea, Republic of (South Korea); 2Dept. of Regulatory Assessment, Korea Institute of Nuclear Safety, Korea, Republic of (South Korea); 3Dept. of Nuclear and Radiation Safety, University of Science and Technology, Republic of (South Korea)
Abstract
The main motivation for this study is to assess the applicability of OpenFOAM to simulate flow inside safety-related pumps in the nuclear power plant. As a preliminary study, steady-state Reynolds averaged Navier-Stokes simulations with a two-equation turbulence model have been conducted by using OpenFOAM on tip leakage flow inside a linear cascade under the design condition, which significantly affects tip leakage vortex, and secondary flow, and rapid pressure change near tip clearance. The pressure and velocity distributions on the both sides of the cascade have been compared with experimental data and the predicted results of a commercial code, ANSYS CFX R18.1. As a result, there has been good agreement between the results of OpenFOAM simulation, and the results of the other comparisons in terms of the pressure and velocity distributions.
Acknowledgement
This work was supported by the Nuclear Safety Research Program through the Korea Foundation Of Nuclear Safety (KOFONS) using the financial resource granted by the Nuclear Safety and Security Commission (NSSC) of the Republic of Korea (No. 1805007).
Prediction of Flow Characteristics by Applying Machine Learning of Shape Change in Fixed Space
Geon-Hong Kim1, Kyeongsik Chang2, Sang-Wook Lee2
1NINANO COMPANY Inc., Korea, Republic of (South Korea); 2University of Ulsan, Korea, Republic of (South Korea)
We have studied how to use machine learning techniques to predict fluid dynamic performance. In the field of traditional CFD, the analysis has been performed by generating a unique mesh system for the object and solving a linear system of equation numerically. Thus, generating a mesh system for analysis has always been a bottleneck of the CFD technique, and various techniques including meshless method have been developed to remedy this problem. Another approach is to apply a machine learning technique to predict the performance of an object due to surrounding fluid flow. Unlike traditional CFD, which obtains a solution, machine learning can be understood as a process of obtaining the coefficient matrix of the system of equations. At this time, the size of the system should be kept constant. However, if the grid system is changed according to the shape, the size changes as well. To tackle this problem, we used the cut-cell method of the immersed boundary method. A predictive model is derived by learning a list of volumes included in the shape as input values and the drag, lift, or velocity components in x, y, and z directions of each cell as output values. The detailed results will be discussed in the presentation.
A hydroelastic study of wave attenuation by a floating plate
Luofeng Huang
University College London, United Kingdom
Considering a floating plate on water surface, its effect of attenuating incoming waves is currently unclear. Especially, when the floating plate is deformable, its bottom boundary induces a complex effect on the transmission fluid. This study investigates how much can wave energy go through the floating plate, particularly, the role played by the elasticity of the plate. From a rigid condition, young modulus of the plate is reducing gradually and the transmitted wave energy is measured. The fluid behaviours underneath the floating plate are also observed to analyse the reason for the attenuation.
To simulate the above problem, a multiphase hydroelastic solver has been developed based on OpenFOAM, with the Navier-Stokes equations describing the fluid domain, the St. Venant Kirchhoff solid model governing the plate deformation and a coupling scheme to achieve the fluid-structure interaction. Thereby, fully coupling has been achieved between wave motion and the elastic deformation of the floating plate. In addition, the new solver has been validated by experiments.
This work can be useful for studying wave transmission over a rigid/elastic floating body, for example, the attenuation of ocean waves along an ice floe, which is of special research interest due to the climate change in the Arctic.
|
