scholarly journals Identifying eigenmodes of averaged small-amplitude perturbations to turbulent channel flow

2019 ◽  
Vol 875 ◽  
pp. 758-780
Author(s):  
A. S. Iyer ◽  
F. D. Witherden ◽  
S. I. Chernyshenko ◽  
P. E. Vincent
Keyword(s):  
Channel Flow ◽  
Small Amplitude ◽  
Direct Evidence ◽  
Graphics Processing Unit ◽  
Turbulence Models ◽  
Turbulent Channel Flow ◽  
Navier Stokes ◽  
Processing Unit ◽  
Graphics Processing ◽  
First Time

Eigenmodes of averaged small-amplitude perturbations to a turbulent channel flow – which is one of the most fundamental canonical flows – are identified for the first time via an extensive set of high-fidelity graphics processing unit accelerated direct numerical simulations. While the system governing averaged small-amplitude perturbations to turbulent channel flow remains unknown, the fact such eigenmodes can be identified constitutes direct evidence that it is linear. Moreover, while the eigenvalue associated with the slowest-decaying anti-symmetric eigenmode mode is found to be real, the eigenvalue associated with the slowest-decaying symmetric eigenmode mode is found to be complex. This indicates that the unknown linear system governing the evolution of averaged small-amplitude perturbations cannot be self-adjoint, even for the case of a uni-directional flow. In addition to elucidating aspects of the flow physics, the findings provide guidance for development of new unsteady Reynolds-averaged Navier–Stokes turbulence models, and constitute a new and accessible benchmark problem for assessing the performance of existing models, which are used widely throughout industry.

Implementation of a Semi-Implicit Pressure-Based Multigrid Fluid Flow Algorithm on a Graphics Processing Unit

2009 ◽  
Author(s):  
Aaron F. Shinn ◽  
S. P. Vanka
Keyword(s):  
Stokes Equations ◽  
Graphics Processing Unit ◽  
Navier Stokes ◽  
Processing Unit ◽  
Navier Stokes Equations ◽  
Driven Cavity ◽  
Multigrid Algorithm ◽  
Computational Speed ◽  
Speed Up ◽  
Graphics Processing

A semi-implicit pressure based multigrid algorithm for solving the incompressible Navier-Stokes equations was implemented on a Graphics Processing Unit (GPU) using CUDA (Compute Unified Device Architecture). The multigrid method employed was the Full Approximation Scheme (FAS), which is used for solving nonlinear equations. This algorithm is applied to the 2D driven cavity problem and compared to the CPU version of the code (written in Fortran) to assess computational speed-up.

scholarly journals Actuator Line Simulations of Wind Turbine Wakes Using the Lattice Boltzmann Method

2019 ◽  
Author(s):  
Henrik Asmuth ◽  
Hugo Olivares-Espinosa ◽  
Stefan Ivanell
Keyword(s):  
Wind Turbine ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Graphics Processing Unit ◽  
Collision Operator ◽  
Scale Model ◽  
Navier Stokes ◽  
Processing Unit ◽  
Boltzmann Method ◽  
Graphics Processing

Abstract. The presented work investigates the potential of large-eddy simulations (LES) of wind turbine wakes using the cumulant lattice Boltzmann method (CLBM). The wind turbine is represented by the actuator line model (ALM) that is implemented in a GPU-accelerated (Graphics Processing Unit) lattice Boltzmann framework. The implementation is validated and discussed by means of a code-to-code comparison to an established finite-volume Navier-Stokes solver. To this end, the ALM is subjected to a uniform laminar inflow while a standard Smagorinsky sub-grid scale model is employed in both numerical approaches. The comparison shows a good agreement in terms of the blade loads and near-wake characteristics. The main differences are found in the point of laminar-turbulent transition of the wake and the resulting far-wake. In line with other studies these differences can be attributed to the different orders of accuracy of the two methods. In a second part the possibilities of implicit LES with the CLBM are investigated using a limiter applied to the third-order cumulants in the scheme's collision operator. The study shows that the limiter generally ensures numerical stability. Nevertheless, a universal tuning approach for the limiter appears to be required, especially for perturbation-sensitive transition studies. In summary, the range of discussed cases outline the general feasibility of wind turbine simulations using the CLBM. In addition, it highlights the potential of GPU-accelerated LBM implementations to significantly speed up LES in the field of wind energy.

Implementing wide baseline matching algorithms on a graphics processing unit.

2007 ◽  
Author(s):  
Fredrick H. Rothganger ◽  
Kurt W. Larson ◽  
Antonio Ignacio Gonzales ◽  
Daniel S. Myers
Keyword(s):  
Graphics Processing Unit ◽  
Processing Unit ◽  
Wide Baseline Matching ◽  
Graphics Processing

scholarly journals Two Decades of 4D-QSAR: A Dying Art or Staging a Comeback?

2021 ◽  
Vol 22 (10) ◽  
pp. 5212
Author(s):  
Andrzej Bak
Keyword(s):  
Molecular Conformation ◽  
Graphics Processing Unit ◽  
Processing Unit ◽  
Diverse Range ◽  
Current State ◽  
Gpu Clusters ◽  
Pharmacophore Hypothesis ◽  
Rising Power ◽  
Graphics Processing ◽  
Ligand Conformation

A key question confronting computational chemists concerns the preferable ligand geometry that fits complementarily into the receptor pocket. Typically, the postulated ‘bioactive’ 3D ligand conformation is constructed as a ‘sophisticated guess’ (unnecessarily geometry-optimized) mirroring the pharmacophore hypothesis—sometimes based on an erroneous prerequisite. Hence, 4D-QSAR scheme and its ‘dialects’ have been practically implemented as higher level of model abstraction that allows the examination of the multiple molecular conformation, orientation and protonation representation, respectively. Nearly a quarter of a century has passed since the eminent work of Hopfinger appeared on the stage; therefore the natural question occurs whether 4D-QSAR approach is still appealing to the scientific community? With no intention to be comprehensive, a review of the current state of art in the field of receptor-independent (RI) and receptor-dependent (RD) 4D-QSAR methodology is provided with a brief examination of the ‘mainstream’ algorithms. In fact, a myriad of 4D-QSAR methods have been implemented and applied practically for a diverse range of molecules. It seems that, 4D-QSAR approach has been experiencing a promising renaissance of interests that might be fuelled by the rising power of the graphics processing unit (GPU) clusters applied to full-atom MD-based simulations of the protein-ligand complexes.

Real-time, High-resolution Depth Upsampling on Embedded Accelerators

2021 ◽  
Vol 20 (3) ◽  
pp. 1-22
Author(s):  
David Langerman ◽  
Alan George
Keyword(s):  
High Resolution ◽  
Low Power ◽  
Real Time ◽  
Mixed Reality ◽  
Graphics Processing Unit ◽  
Processing Unit ◽  
Reconfigurable Logic ◽  
Depth Sensors ◽  
Time Requirements ◽  
Graphics Processing

High-resolution, low-latency apps in computer vision are ubiquitous in today’s world of mixed-reality devices. These innovations provide a platform that can leverage the improving technology of depth sensors and embedded accelerators to enable higher-resolution, lower-latency processing for 3D scenes using depth-upsampling algorithms. This research demonstrates that filter-based upsampling algorithms are feasible for mixed-reality apps using low-power hardware accelerators. The authors parallelized and evaluated a depth-upsampling algorithm on two different devices: a reconfigurable-logic FPGA embedded within a low-power SoC; and a fixed-logic embedded graphics processing unit. We demonstrate that both accelerators can meet the real-time requirements of 11 ms latency for mixed-reality apps. 1

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