scholarly journals Towards Multiscale Modeling of Ocean Surface Turbulent Mixing Using Coupled MPAS-Ocean v6.3 and PALM v5.0

2020 ◽  
Author(s):  
Qing Li ◽  
Luke Van Roekel
Keyword(s):  
Large Eddy Simulation ◽  
Multiscale Modeling ◽  
Turbulent Mixing ◽  
Three Dimensional ◽  
Ocean Surface ◽  
Global Ocean ◽  
High Fidelity ◽  
Processing Unit ◽  
Eddy Simulation ◽  
Large Eddy

Abstract. A multiscale modeling approach for studying the ocean surface turbulent mixing is explored by coupling an ocean general circulation model (GCM) MPAS-Ocean with the PArallel Large eddy simulation Model (PALM). The coupling approach is similar to the superparameterization approach that has been used mostly to represent the effects of deep convection in atmospheric GCMs. However, since the emphasis here is on the small-scale turbulent mixing processes and their interactions with the larger-scale processes, a high-fidelity, three-dimensional large eddy simulation (LES) model is used, in contrary to a simplified process-resolving model with reduced physics or reduced dimension commonly used in the superparameterization literature. To reduce the computational cost, a customized version of PALM is ported on the general-purpose graphics processing unit (GPU) with OpenACC, achieving 10–16 times overall speedup as compared to running on a single CPU. Even with the GPU-acceleration technique, superparameterization of the ocean surface turbulent mixing using high-fidelity and three-dimensional LES over the global ocean in GCMs is still computationally intensive and infeasible for long simulations. However, running PALM regionally on selected MPAS-Ocean grid cells is shown to be a promising approach moving forward. The flexible coupling between MPAS-Ocean and PALM outlined here allows further exploration of the interactions between ocean surface turbulent mixing and larger-scale processes, and development of better ocean surface turbulent mixing parameterizations in GCMs.

scholarly journals Towards multiscale modeling of ocean surface turbulent mixing using coupled MPAS-Ocean v6.3 and PALM v5.0

2021 ◽  
Vol 14 (4) ◽  
pp. 2011-2028
Author(s):  
Qing Li ◽  
Luke Van Roekel
Keyword(s):  
Multiscale Modeling ◽  
Turbulent Mixing ◽  
General Circulation ◽  
Ocean Surface ◽  
Global Ocean ◽  
Small Scale ◽  
Processing Unit ◽  
Flexible Coupling ◽  
Modeling Approach ◽  
Large Eddy

Abstract. A multiscale modeling approach for studying the ocean surface turbulent mixing is explored by coupling an ocean general circulation model (GCM) MPAS-Ocean with the Parallelized Large Eddy Simulation Model (PALM). The coupling approach is similar to the superparameterization approach that has been used to represent the effects of deep convection in atmospheric GCMs. However, the focus of this multiscale modeling approach is on the small-scale turbulent mixing and their interactions with the larger-scale processes in the ocean, so that a more flexible coupling strategy is used. To reduce the computational cost, a customized version of PALM is ported on the general-purpose graphics processing unit (GPU) with OpenACC, achieving 10–16 times overall speedup as compared to running on a single CPU. Even with the GPU-acceleration technique, a superparameterization-like approach to represent the ocean surface turbulent mixing in GCMs using embedded high fidelity and three-dimensional large eddy simulations (LESs) over the global ocean is still computationally intensive and infeasible for long simulations. However, running PALM regionally on selected MPAS-Ocean grid cells is shown to be a promising approach moving forward. The flexible coupling between MPAS-Ocean and PALM allows further exploration of the interactions between the ocean surface turbulent mixing and larger-scale processes, as well as future development and improvement of ocean surface turbulent mixing parameterizations for GCMs.

Noise Prediction of Pressure-Mismatched Jets Using Unstructured Large Eddy Simulation

2011 ◽  
Author(s):  
Yaser Khalighi ◽  
Frank Ham ◽  
Parviz Moin ◽  
Sanjiva K. Lele ◽  
Robert H. Schlinker
Keyword(s):  
Large Eddy Simulation ◽  
Turbulent Flow ◽  
Three Dimensional ◽  
Empirical Models ◽  
Nozzle Geometry ◽  
High Fidelity ◽  
Noise Generation ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Generation Mechanisms

It is our premise that significant new advances in the understanding of noise generation mechanisms for jets and realistic methods for reducing this noise can be developed by exploiting high-fidelity computational fluid dynamics: namely large eddy simulation (LES). In LES, the important energy-containing structures in the flow are resolved explicitly, resulting in a time-dependent, three-dimensional realization of the turbulent flow. In the context of LES, the unsteady flow occurring in the jet plume (and its associated sound) can be accurately predicted without resort to adjustable empirical models. In such a framework, the nozzle geometry can be included to directly influence the turbulent flow including its coherent and fine-scale motions. The effects of propulsion system design choices and issues of integration with the airframe can also be logically addressed.

Accelerating unstructured large eddy simulation solver with GPU

2018 ◽  
Vol 35 (5) ◽  
pp. 2025-2049 ◽  
Author(s):  
Hongbin Liu ◽  
Xinrong Su ◽  
Xin Yuan
Keyword(s):  
Large Eddy Simulation ◽  
Finite Volume ◽  
Three Dimensional ◽  
Finite Volume Scheme ◽  
High Fidelity ◽  
Double Precision ◽  
Content Type ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Speed Up

Purpose Adopting large eddy simulation (LES) to simulate the complex flow in turbomachinery is appropriate to overcome the limitation of current Reynolds-Averaged Navier–Stokes modelling and it provides a deeper understanding of the complicated transitional and turbulent flow mechanism; however, the large computational cost limits its application in high Reynolds number flow. This study aims to develop a three-dimensional GPU-enabled parallel-unstructured solver to speed up the high-fidelity LES simulation. Design/methodology/approach Compared to the central processing units (CPUs), graphics processing units (GPUs) can provide higher computational speed. This work aims to develop a three-dimensional GPU-enabled parallel-unstructured solver to speed up the high-fidelity LES simulation. A set of low-dissipation schemes designed for unstructured mesh is implemented with compute unified device architecture programming model. Several key parameters affecting the performance of the GPU code are discussed and further speed-up can be obtained by analysing the underlying finite volume-based numerical scheme. Findings The results show that an acceleration ratio of approximately 84 (on a single GPU) for double precision algorithm can be achieved with this unstructured GPU code. The transitional flow inside a compressor is simulated and the computational efficiency has been improved greatly. The transition process is discussed and the role of K-H instability playing in the transition mechanism is verified. Practical/implications The speed-up gained from GPU-enabled solver reaches 84 compared to original code running on CPU and the vast speed-up enables the fast-turnaround high-fidelity LES simulation. Originality/value The GPU-enabled flow solver is implemented and optimized according to the feature of finite volume scheme. The solving time is reduced remarkably and the detail structures including vortices are captured.

Large‐Eddy Simulation of Three‐Dimensional Flow Structures Over Wave‐generated Ripples

2021 ◽  
Author(s):  
Chuang Jin ◽  
Giovanni Coco ◽  
Rafael O. Tinoco ◽  
Pallav Ranjan ◽  
Jorge San Juan ◽  
...  
Keyword(s):  
Large Eddy Simulation ◽  
Three Dimensional ◽  
Flow Structures ◽  
Three Dimensional Flow ◽  
Dimensional Flow ◽  
Eddy Simulation ◽  
Large Eddy

Large Eddy Simulation of Cross Flow in Pipe Junction

2018 ◽  
Author(s):  
Jiajun Chen ◽  
Yue Sun ◽  
Hang Zhang ◽  
Dakui Feng ◽  
Zhiguo Zhang
Keyword(s):  
Large Eddy Simulation ◽  
Stokes Equations ◽  
Numerical Study ◽  
Three Dimensional ◽  
Cross Flow ◽  
Exciting Force ◽  
Navier Stokes ◽  
Pipe Network ◽  
Eddy Simulation ◽  
Large Eddy

Mixing in pipe junctions can play an important role in exciting force and distribution of flow in pipe network. This paper investigated the cross pipe junction and proposed an improved plan, Y-shaped pipe junction. The numerical study of a three-dimensional pipe junction was performed for calculation and improved understanding of flow feature in pipe. The filtered Navier–Stokes equations were used to perform the large-eddy simulation of the unsteady incompressible flow in pipe. From the analysis of these results, it clearly appears that the vortex strength and velocity non-uniformity of centerline, can be reduced by Y-shaped junction. The Y-shaped junction not only has better flow characteristic, but also reduces head loss and exciting force. The results of the three-dimensional improvement analysis of junction can be used in the design of pipe network for industry.

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