Direct Numerical Simulation of Laminar-Turbulent Transition in a Flared Cone Boundary Layer at Mach 6

2016 ◽  
Author(s):  
Jayahar Sivasubramanian ◽  
Hermann F. Fasel
Keyword(s):  
Numerical Simulation ◽  
Boundary Layer ◽  
Direct Numerical Simulation ◽  
Turbulent Transition ◽  
Laminar Turbulent Transition

Direct Numerical Simulation on Transition of an Incompressible Boundary Layer on a Flat Plate

2012 ◽  
Vol 268-270 ◽  
pp. 1143-1147
Author(s):  
Ning Li ◽  
Qi Hong Zeng
Keyword(s):  
Numerical Simulation ◽  
Boundary Layer ◽  
Direct Numerical Simulation ◽  
Flat Plate ◽  
Flow Profile ◽  
Mean Flow ◽  
Turbulent Transition ◽  
Incompressible Boundary Layer ◽  
Incompressible Boundary ◽  
Laminar Turbulent Transition

Direct Numerical Simulation(DNS) was carried out for laminar-turbulent transition of an incompressible boundary layer on a flat plate based on disturbance Navier-Stokes(N-S) equation in spatial mode with Massage Passing Interface(MPI) technology. Study on breakdown mechanism of laminar-turbulent transition was carried on. The effect of mean flow distortion on the process of breakdown in laminar-turbulent transition was investigated. Results indicate that change of instability characteristic of mean flow profile plays a key role during process of breakdown.

Validation of the PTM Transition Model on a 3D Flow Through a Turbine Cascade

2016 ◽  
Author(s):  
Sergiy Yershov ◽  
Viktor Yakovlev
Keyword(s):  
Numerical Simulation ◽  
Boundary Layer ◽  
Numerical Results ◽  
Transitional Flow ◽  
Turbine Cascade ◽  
Production Term ◽  
Flow Acceleration ◽  
Turbulent Transition ◽  
Displacement Thickness ◽  
Laminar Turbulent Transition

This study presents a numerical simulation of a 3D viscous subsonic flow in the VKI-Genoa turbine cascade taking into account the laminar-turbulent transition. The numerical simulation is performed using the Reynolds-averaged Navier-Stokes (RANS) equations and the low-Reynolds k-ω SST turbulence model. The Langtry’s algebraic Production Term Modification (PTM) model is applied for modeling the laminar-turbulent transition. The governing equations are integrated using the second-order accurate Godunov’s type implicit ENO scheme. Computations of both fully turbulent and transitional flows are carried out. Much attention is given to the comparison between the present numerical results and the existing experimental data. The comparison was based on the surface distributions of the isentropic velocity, the friction velocity, the flow acceleration parameter, the displacement thickness, the shape-factor, and the momentum thickness Reynolds number. Velocity profiles upstream and downstream of the transition onset were compared also. The numerical results obtained show an influence of the transition on the secondary flow pattern. In the case of the transitional flow, when compared with the fully turbulence flow case, the endwall boundary layer cross-flow starts upstream, and it is more intensive, but less massive due to a thinner boundary layer in the laminar flow region.

scholarly journals Application of multiGPU+CPU architecture for the direct numerical simulation of laminar-turbulent transition

2016 ◽  
pp. 55-64
Author(s):  
Н.М. Евстигнеев ◽  
О.И. Рябков
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
System Analysis ◽  
Algorithm Optimization ◽  
Statistical Parameters ◽  
Turbulent Transition ◽  
System Analysis Approach ◽  
Monodromy Matrices ◽  
Hardware Efficiency ◽  
Laminar Turbulent Transition

Обобщаются данные о применении различных параллельных вычислительных архитектур при численном моделировании задач ламинарно-турбулентного перехода (ЛТП). Обычно анализ ЛТП основан на рассмотрении статистических параметров: корреляций пульсаций скорости, энергетических спектров и др. Анализ ЛТП как нелинейной динамической системы в дополнение к уже указанному анализу основан на анализе собственных значений якобиана, вида аттракторов систем в фазовом пространстве и собственных значений матрицы монодромии. В результате строятся бифуркационные сценарии и диаграммы. Это дает возможность проследить механизм усложнения для рассматриваемых задач при ЛТП при изменении выбранных параметров (чисел Рейнольдса, Маха, Фруда и др.). Рассмотрение процесса ЛТП с точки зрения нелинейных динамических систем накладывает требования точности и быстродействия используемых алгоритмов решения задач. Начиная с 2008 г. в наших работах используются GPU- и multiGPU-архитектуры совместно с CPU. За это время было рассмотрено восемь постановок задач ЛТП. Для численного моделирования применялись различные методы высокого порядка. В настоящей статье для каждого класса методов рассматриваются характерные вычислительные операции, приводятся использованные библиотеки и выполняется сравнение эффективности разработанных алгоритмов и примененных библиотек с CPU-версиями кода, а также между собой. Показано, что в среднем на один GPU по сравнению с CPU ускорение варьируется от 5 до 35 раз. В связи со сложностью алгоритмов при MPI CPU- и multiGPU-подходах ускорение редко бывает линейным и оно пропорционально степенной функции с показателем 0.78-0.81. Для multiGPU-анализа алгоритмы тестировались на пяти GPU. Обсуждаются результаты при гибридном применении CPU+multiGPU для одной из задач. The use of various parallel computational architectures for the direct numerical simulation (DNS) of laminar-turbulent transition problems (LTTPs) is summarized. Usually, DNS results are analyzed on the basis of a set of statistical parameters: pulsation velocities correlations, energy spectra, etc. When a dynamical system analysis approach is applied to DNS results, it is necessary to evaluate additional parameters: eigenvalues of Jacobi matrices, phase space attractors, and eigenvalues of monodromy matrices, etc. This allows one to present results as bifurcation scenarios and diagrams and bring up more details concerning LTTP scenario as functions of bifurcation parameters (e.g., Reynolds, Mach, and Froude numbers). This problem is computationally expensive and algorithms are complex. This brings up more demands on the hardware efficiency and software algorithm optimization. We are using GPU and multiGPU together with CPU architectures since 2008 for this kind of DNS. We considered eight different LTTPs since then. Various high-order methods were applied. In this paper we show typical computational operations for each class of problem. We illustrate the application of libraries and algorithms, perform efficiency benchmarking across GPUs and with CPU versions. It is shown that in general one GPU is 5 to 35 times faster than CPU. The acceleration is worse than linear and is proportional to a power function with an exponent between 0.78 and 0.81. We use five GPUs for multiGPU and show CPU+multiGPU efficiency for one of the problems under consideration.

Numerical Simulation of the boundary layer laminar-turbulent transition caused by a small gap

2021 ◽  
Author(s):  
Felipe Oliveira Aguirre ◽  
Marlon Sproesser Mathias ◽  
Marcello Augusto Faraco de Medeiros
Keyword(s):  
Numerical Simulation ◽  
Boundary Layer ◽  
Turbulent Transition ◽  
Laminar Turbulent Transition

INFLUENCE OF THE PLATE LEADING-EDGE SHAPE AND THICKNESS ON THE BOUNDARY LAYER LAMINAR-TURBULENT TRANSITION IN HYPERSONIC FLOW

2019 ◽  
Vol 50 (5) ◽  
pp. 461-481
Author(s):  
Sergei Vasilyevich Aleksandrov ◽  
Evgeniya Andreevna Aleksandrova ◽  
Volf Ya. Borovoy ◽  
Andrey Vyacheslavovich Gubernatenko ◽  
Vladimir Evguenyevich Mosharov ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Hypersonic Flow ◽  
Leading Edge ◽  
Turbulent Transition ◽  
Laminar Turbulent Transition
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