Vortex core identification in viscous hydrodynamics

2005 ◽  
Vol 363 (1833) ◽  
pp. 1937-1948 ◽  
Author(s):  
Lucas I Finn ◽  
Bruce M Boghosian ◽  
Christopher N Kottke
Keyword(s):  
Software Package ◽  
Message Passing ◽  
Message Passing Interface ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Computational Steering ◽  
Navier Stokes Equations ◽  
Viscous Hydrodynamics ◽  
Knots And Links ◽  
User Intervention

We describe a software package designed for the investigation of topological fluid dynamics with a novel algorithm for locating and tracking vortex cores. The package is equipped with modules for generating desired vortex knots and links and evolving them according to the Navier–Stokes equations, while tracking and visualizing them. The package is parallelized using a message passing interface for a multiprocessor environment and makes use of a computational steering library for dynamic user intervention.

scholarly journals Asynchronous Parallelization of a CFD Solver

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Daniel S. Abdi ◽  
Girma T. Bitsuamlak
Keyword(s):  
Message Passing ◽  
Message Passing Interface ◽  
Stokes Equations ◽  
Domain Decomposition Method ◽  
Asynchronous Communication ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Asynchronous Iterations ◽  
Alternative Approach ◽  
Asynchronous Methods

A Navier-Stokes equations solver is parallelized to run on a cluster of computers using the domain decomposition method. Two approaches of communication and computation are investigated, namely, synchronous and asynchronous methods. Asynchronous communication between subdomains is not commonly used in CFD codes; however, it has a potential to alleviate scaling bottlenecks incurred due to processors having to wait for each other at designated synchronization points. A common way to avoid this idle time is to overlap asynchronous communication with computation. For this to work, however, there must be something useful and independent a processor can do while waiting for messages to arrive. We investigate an alternative approach of computation, namely, conducting asynchronous iterations to improve local subdomain solution while communication is in progress. An in-house CFD code is parallelized using message passing interface (MPI), and scalability tests are conducted that suggest asynchronous iterations are a viable way of parallelizing CFD code.

scholarly journals To the issue of evaluating sonic boom overpressure and loudness

2019 ◽  
Vol 304 ◽  
pp. 02003
Author(s):  
Igor G. Bashkirov ◽  
Sergey L. Chernyshev ◽  
Vladlen S. Gorbovskoy ◽  
Andrey V. Kazhan ◽  
Vyacheslav G. Kazhan ◽  
...  
Keyword(s):  
Software Package ◽  
Stokes Equations ◽  
Aerodynamic Drag ◽  
Near Field ◽  
Theoretical Data ◽  
Aerodynamic Characteristics ◽  
Sonic Boom ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Computational Mesh

At present, in the world there is a growing interest in the development of a new generation of supersonic passenger aircraft. One of the main problems of creating such aircraft is to ensure both an acceptable sonic boom level and high aerodynamic characteristics in the supersonic cruising mode. This requires the development of reliable methods for obtaining the near field under the plane with taking into account the influence of the boundary layer, calculation of overpressure signature on the ground and evaluation of sonic boom loudness. In this work four variants of the equivalent body of revolution of minimum sonic boom with different nose sharpening were investigated for an aircraft weighing 19 tons in supersonic cruising flight at Mach number of 1.7 and altitude of 15.5 km using the software package for solving the Reynolds–averaged Navier–Stokes equations (RANS) ANSYS CFX. A macro for calculating the overpressure signature on the ground for the distribution of disturbances in the near field under the aircraft and a program for evaluating the sonic boom loudness in various metrics were developed. Computational mesh verification of the results was carried out, the obtained overpressure signatures were compared with theoretical data and calculation results from the software package for the integration of complete system of Euler equations by finite–difference method X–CODE. The effect of the sharpening of the nose part on aerodynamic drag and sound boom characteristics was shown. The work was done in the interests of the international project RUMBLE (RegUlation and norM for low sonic Boom LEvels).

Parallel, Multi-Zone, Multi-Block Solver to Study Arterial Branches in Human Vascular System

2001 ◽  
Author(s):  
M. Tadjfar ◽  
R. Himeno
Keyword(s):  
Message Passing ◽  
Incompressible Flows ◽  
Stokes Equations ◽  
Vascular System ◽  
Three Dimensional ◽  
Data Partitioning ◽  
Parallel Execution ◽  
Navier Stokes ◽  
Computational Domain ◽  
Navier Stokes Equations

Abstract The unsteady, three-dimensional, incompressible Navier-Stokes equations are solved numerically to study arterial branches in human vascular system. The solver is capable of dealing with moving boundaries and moving grids. It is designed to handle complex, three-dimensional vascular systems. The computational domain is divided into multiple block subdomains. At each cross section the plane is divided into twelve sub-zones to allow flexibility for handling complex geometries and, if needed, appropriate parallel data partitioning. A second-order in time and third-order upwind finite volume method for solving time-accurate incompressible flows based on pseudo-compressibility and dual time-stepping technique is used. For parallel execution, the flow domain is partitioned. Communication between the subdomains of the flow on Riken’s VPP/700E supercomputer is implemented using MPI message-passing library. The code is capable of running on both shared and/or distributed memory architectures.

SLIDING FRICTION IN VISCOUS HYDRODYNAMICS: THE ROUGH SURFACE AS VORTICITY SOURCE

1989 ◽  
Vol 03 (05) ◽  
pp. 393-397
Author(s):  
H. DEKKER
Keyword(s):  
Friction Coefficient ◽  
Viscous Fluid ◽  
Rough Surface ◽  
Solid Surface ◽  
Sliding Friction ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Vorticity Source ◽  
Viscous Hydrodynamics

Basset’s collective friction coefficient for a viscous fluid flowing past a rough solid surface is obtained — analytically — as an intrinsic consequence of the Navier-Stokes equations by treating the surface as a source of vorticity.

scholarly journals Modelling of the flow in front of the jet obstacle at variation of oncoming flow parameters

2021 ◽  
pp. 1-14
Author(s):  
Alexander Evgenyevich Bondarev ◽  
Artyom Evgenyevich Kuvshinnikov ◽  
Tatiana Nikolaevna Mikhailova ◽  
Irina Gennadievna Ryzhova ◽  
Lev Zalmanovich Shapiro
Keyword(s):  
Software Package ◽  
Boundary Layer Thickness ◽  
Stokes Equations ◽  
Laminar Flows ◽  
Navier Stokes ◽  
Incoming Flow ◽  
Oncoming Flow ◽  
Input Flow ◽  
Navier Stokes Equations ◽  
Flow Parameters

The results of numerical simulation of the problem of interaction of supersonic flow with a jet obstacle under variation of input flow parameters are considered. The problem is solved in the system of Navier-Stokes equations. Laminar flows are considered. The qualitative flow pattern has been studied under the variation of incoming flow velocity and boundary layer thickness in the incoming flow. The calculations were performed using the OpenFOAM software package.

Parallel Solver for Blood Flow in Human Vascular System

2000 ◽  
Author(s):  
M. Tadjfar ◽  
T. Yamaguchi ◽  
R. Himeno
Keyword(s):  
Blood Flow ◽  
Message Passing ◽  
Incompressible Flows ◽  
Stokes Equations ◽  
Vascular System ◽  
Three Dimensional ◽  
Parallel Execution ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Volume Method

Abstract In order to simulate blood flow in human vascular system, the unsteady, three-dimensional, incompressible Navier-Stokes equations are solved numerically. The solver is capable of dealing with moving boundaries and moving grids. A second-order in time and third-order upwind finite volume method for solving time-accurate incompressible flows utilizing pseudo-compressibility technique is used. For parallel execution, the flow domain is partitioned. Communication between the subdomains of the flow on Riken’s VPP/700E supercomputer is implemented using MPI message-passing library. The code is capable of running on both shared and/or distributed memory architectures.

Effects of stator splitter blades on aerodynamic performance of a single-stage transonic axial compressor

2020 ◽  
Vol 14 (4) ◽  
pp. 7369-7378
Author(s):  
Ky-Quang Pham ◽  
Xuan-Truong Le ◽  
Cong-Truong Dinh
Keyword(s):  
Stokes Equations ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Aerodynamic Performance ◽  
Numerical Results ◽  
Single Stage ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Operating Stability ◽  
Length Coverage

Splitter blades located between stator blades in a single-stage axial compressor were proposed and investigated in this work to find their effects on aerodynamic performance and operating stability. Aerodynamic performance of the compressor was evaluated using three-dimensional Reynolds-averaged Navier-Stokes equations using the k-e turbulence model with a scalable wall function. The numerical results for the typical performance parameters without stator splitter blades were validated in comparison with experimental data. The numerical results of a parametric study using four geometric parameters (chord length, coverage angle, height and position) of the stator splitter blades showed that the operational stability of the single-stage axial compressor enhances remarkably using the stator splitter blades. The splitters were effective in suppressing flow separation in the stator domain of the compressor at near-stall condition which affects considerably the aerodynamic performance of the compressor.

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