scholarly journals Parallel Mesh Adaptive Techniques Illustrated with Complex Compressible Flow Simulations

2012 ◽  
Vol 2012 ◽  
pp. 1-14 ◽  
Author(s):  
Pénélope Leyland ◽  
Angelo Casagrande ◽  
Yannick Savoy
Keyword(s):  
Unstructured Grids ◽  
Mesh Adaptation ◽  
Computational Time ◽  
A Posteriori ◽  
Parallel Solution ◽  
Flow Simulations ◽  
Grid Adaption ◽  
Solution Accuracy ◽  
2D And 3D ◽  
Time Grid

The aim of this paper is to discuss efficient adaptive parallel solution techniques on unstructured 2D and 3D meshes. We concentrate on the aspect of parallel a posteriori mesh adaptation. One of the main advantages of unstructured grids is their capability to adapt dynamically by localised refinement and derefinement during the calculation to enhance the solution accuracy and to optimise the computational time. Grid adaption also involves optimisation of the grid quality, which will be described here for both structural and geometrical optimisation.

scholarly journals Parallel Mesh Adaptive Techniques for Complex Flow Simulation: Geometry Conservation

2012 ◽  
Vol 2012 ◽  
pp. 1-13
Author(s):  
Angelo Casagrande ◽  
Pénélope Leyland ◽  
Luca Formaggia
Keyword(s):  
Computer Aided Design ◽  
Unstructured Grids ◽  
Flow Simulation ◽  
Mesh Adaptation ◽  
Computational Time ◽  
Complex Flow ◽  
Efficient Tool ◽  
Refinement Process ◽  
Solution Accuracy ◽  
Aided Design

Dynamic mesh adaptation on unstructured grids, by localised refinement and derefinement, is a very efficient tool for enhancing solution accuracy and optimising computational time. One of the major drawbacks, however, resides in the projection of the new nodes created, during the refinement process, onto the boundary surfaces. This can be addressed by the introduction of a library capable of handling geometric properties given by a CAD (computer-aided design) description. This is of particular interest also to enhance the adaptation module when the mesh is being smoothed, and hence moved, to then reproject it onto the surface of the exact geometry.

Multi-Objective Hydro-Thermal Scheduling Problem Using Two Novel Optimization Techniques

2021 ◽  
Vol 12 (3) ◽  
pp. 1-36
Author(s):  
Provas Kumar Roy ◽  
Moumita Pradhan ◽  
Tandra Pal
Keyword(s):  
Power Systems ◽  
Test System ◽  
Optimization Techniques ◽  
Computational Time ◽  
Environmental Aspects ◽  
Grey Wolf Optimization ◽  
Multi Objective ◽  
Efficiency And Effectiveness ◽  
Loading Effects ◽  
Solution Accuracy

This article describes an efficient and reliable strategy for the scheduling of nonlinear multi-objective hydrothermal power systems using the grey wolf optimization (GWO) technique. Moreover, the theory of oppositional-based learning (OBL) is integrated with original GWO for further enhancing its convergence rate and solution accuracy. The constraints related to hydro and thermal plants and environmental aspects are also considered in this paper. To show its efficiency and effectiveness, the proposed GWO and OGWO algorithms are authenticated for the test system consisting of a multi-chain cascade of 4 hydro and 3 thermal units whose valve-point loading effects are also taken into account. Furthermore, statistical outcomes of the conventional heuristic approaches available in the literature are compared with the proposed GWO and OGWO approaches, and these methods give moderately better operational fuel cost and emission in less computational time.

Novel use of AMR Unstructured Grids in DSMC Compressible Flow Simulations

2017 ◽  
Author(s):  
Saurabh Sawant ◽  
Ozgur Tumuklu ◽  
Revathi Jambunathan ◽  
Deborah A. Levin
Keyword(s):  
Compressible Flow ◽  
Unstructured Grids ◽  
Flow Simulations

scholarly journals A Parallel Adaptive Newton-Krylov-Schwarz Method for 3D Compressible Inviscid Flow Simulations

2013 ◽  
Vol 2013 ◽  
pp. 1-16 ◽  
Author(s):  
Marzio Sala ◽  
Pénélope Leyland ◽  
Angelo Casagrande
Keyword(s):  
Compressible Flows ◽  
Time Derivative ◽  
Inviscid Flow ◽  
Implicit Time ◽  
Residual Distribution ◽  
Preconditioning Techniques ◽  
Flow Simulations ◽  
Efficient Data ◽  
Time Marching ◽  
2D And 3D

A parallel adaptive pseudo transient Newton-Krylov-Schwarz (αΨNKS) method for the solution of compressible flows is presented. Multidimensional upwind residual distribution schemes are used for space discretisation, while an implicit time-marching scheme is employed for the discretisation of the (pseudo)time derivative. The linear system arising from the Newton method applied to the resulting nonlinear system is solved by the means of Krylov iterations with Schwarz-type preconditioners. A scalable and efficient data structure for theαΨNKS procedure is presented. The main computational kernels are considered, and an extensive analysis is reported to compare the Krylov accelerators, the preconditioning techniques. Results, obtained on a distributed memory computer, are presented for 2D and 3D problems of aeronautical interest on unstructured grids.

Compressible Flow Simulations on a Massively Parallel Computer

1991 ◽  
Vol 02 (01) ◽  
pp. 430-436
Author(s):  
ELAINE S. ORAN ◽  
JAY P. BORIS
Keyword(s):  
Compressible Flow ◽  
Chemical Reactions ◽  
Large Scale ◽  
Model Development ◽  
Time Dependent ◽  
Parallel Computer ◽  
Massively Parallel ◽  
Parallel Solution ◽  
Flow Simulations ◽  
Connection Machine

This paper describes model development and computations of multidimensional, highly compressible, time-dependent reacting on a Connection Machine (CM). We briefly discuss computational timings compared to a Cray YMP speed, optimal use of the hardware and software available, treatment of boundary conditions, and parallel solution of terms representing chemical reactions. In addition, we show the practical use of the system for large-scale reacting and nonreacting flows.

Comparison of Different Acceleration Techniques and Methods for Periodic Boundary Treatment in Unsteady Turbine Stage Flow Simulations

1999 ◽  
Author(s):  
Martin von Hoyningen-Huene ◽  
Alexander R. Jung
Keyword(s):  
Unsteady Flow ◽  
Numerical Method ◽  
Periodic Boundary ◽  
Computational Time ◽  
Test Case ◽  
The Real ◽  
Flow Simulations ◽  
Time Stepping ◽  
Acceleration Techniques ◽  
Pitch Ratio

This paper studies different acceleration techniques for unsteady flow calculations. The results are compared with a non-accelerated, fully-explicit solution in terms of time-averaged pressure distributions, the unsteady pressure and entropy in the frequency domain and the skin friction factor. The numerical method solves the unsteady three-dimensional Navier-Stokes equations via an explicit time-stepping procedure. The flow in the first stage of a modern industrial gas turbine is chosen as a test case. After a description of the numerical method used for the simulation, the test case is introduced. The comparison of the different numerical algorithms for explicit schemes is intended to ease the decision about which acceleration technique to use for calculations as far as accuracy and computational time are concerned. The convergence acceleration methods under consideration are, respectively, explicit time-stepping with implicit residual averaging, explicit time-consistent multigrid and implicit dual time stepping. The investigation and comparison of the different acceleration techniques are applicable to all explicit unsteady flow solvers. As another point of interest, the influence of the stage blade count ratio on the flow field is investigated. For this purpose, a simulation with a stage pitch ratio of unity is compared with a calculation using the real ratio of 78:80, which requires a more sophisticated method for periodic boundary condition treatment. This paper should help to decide whether it is vital from the turbine designer’s point of view to model the real pitch ratio in unsteady flow simulations in turbine stages.

Meshing Method for Transient Computation With Complex Geometry in CFD

2002 ◽  
Author(s):  
J. L. Kueny ◽  
B. Dore´ ◽  
G. Coppens
Keyword(s):  
Complex Geometry ◽  
Mesh Adaptation ◽  
Moving Mesh ◽  
Computational Time ◽  
Tangential Displacement ◽  
Time Step ◽  
Local Observation ◽  
Complex Boundary ◽  
Accuracy Of Results ◽  
Main Ideas

The description of mesh evolution during a transient computation with moving walls and mesh adaptation has to respect many rules. Using a good mesh for each computational time step is important for accuracy of results. The complexity of geometry can make this objective more complex. A method has been developed to obtain a good moving mesh description with complex boundary geometry. It is based on a local observation of boundary movement and can be resumed by two main ideas: • Add cells where the volume of solution domain increases. • Slide the mesh where the boundary has a tangential displacement.

Parallel Multiblock Mixed Finite Element Method for Elliptic Problems on Unstructured Grids

2002 ◽  
Author(s):  
Darrell W. Pepper ◽  
Jichun Li
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Unstructured Grids ◽  
Mixed Finite Element ◽  
Elliptic Problems ◽  
Mixed Finite Element Method ◽  
Numerical Results ◽  
2D And 3D ◽  
Element Method

In this paper, we develop a general multiblock mixed finite element method for solving 2D and 3D elliptic problems by different unstructured grids on both serial and parallel platforms. Detailed implementations and numerical results are presented.

Sign in / Sign up

Export Citation Format

Share Document