Development of an overset grid computational fluid dynamics solver on graphical processing units

The accurate prediction of unsteady aerodynamic performance and loads, for floating offshore wind turbines (FOWTs), is still questionable because several conventional methods widely used for this purpose are applied in ways that violate the theoretical assumptions of their original formulation. The major objective of the present study is to investigate the unsteady aerodynamic effects for the rotating blade due to the periodic surge motions of an FOWT. This work was conducted using several numerical approaches, particularly unsteady computational fluid dynamics (CFD) with an overset grid-based approach. The unsteady aerodynamic effects that occur when an FOWT is subjected to the surge motion of its floating support platform is assumed as a sinusoidal function. The present CFD simulation based on an overset grid approach provides a sophisticated numerical model on complex flows around the rotating blades simultaneously having the platform surge motion. In addition, an in-house unsteady blade element momentum (UBEM) and the fast (fatigue, aerodynamic, structure, and turbulence) codes are also applied as conventional approaches. The unsteady aerodynamic performances and loads of the rotating blade are shown to be changed considerably depending on the amplitude and frequency of the platform surge motion. The results for the flow interaction phenomena between the oscillating motions of the rotating wind turbine blades and the generated blade-tip vortices are presented and investigated in detail.

Download Full-text

PEGASUS 5: An Automated Preprocessor for Overset-Grid Computational Fluid Dynamics

AIAA Journal ◽

10.2514/2.2070 ◽

2003 ◽

Vol 41 (6) ◽

pp. 1037-1045 ◽

Cited By ~ 100

Author(s):

Stuart E. Rogers ◽

Norman E. Suhs ◽

William E. Dietz

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Overset Grid

Download Full-text

A Technological Effect Modeling on Complex Turbomachinery Applications With an Overset Grid Numerical Method

Journal of Turbomachinery ◽

10.1115/1.4027997 ◽

2014 ◽

Vol 136 (10) ◽

Cited By ~ 7

Author(s):

Lionel Castillon ◽

Gilles Billonnet ◽

Jacques Riou ◽

Stéphanie Péron ◽

Christophe Benoit

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Numerical Simulations ◽

Tip Clearance ◽

Overset Grid ◽

Grid Approach ◽

Computational Fluid Dynamics Cfd ◽

Geometrical Effects ◽

The Impact ◽

Casing Treatments

This paper presents an overview of numerical simulations performed at ONERA on turbomachinery configurations which include technological effects, such as tip clearance, hub disk leakage, circumferential and noncircumferential casing treatments (CTs), blade fillets, and cooling holes. An overset grid approach (Chimera technique) is used to simulate these geometrical effects with ONERA's structured computational fluid dynamics (CFD) solver elsA. Calculations performed on the different configurations enable to quantify the impact of these technological effects on the flow solution.

Download Full-text

Computational Fluid Dynamics Computations Using a Preconditioned Krylov Solver on Graphical Processing Units

Journal of Fluids Engineering ◽

10.1115/1.4031159 ◽

2015 ◽

Vol 138 (1) ◽

Cited By ~ 1

Author(s):

Amit Amritkar ◽

Danesh Tafti

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Pipe Flow ◽

Turbulent Channel Flow ◽

General Purpose ◽

Processing Unit ◽

Double Precision ◽

Single Precision ◽

Central Processing ◽

Graphical Processing

Graphical processing unit (GPU) computation in recent years has seen extensive growth due to advancement in both hardware and software stack. This has led to increase in the use of GPUs as accelerators across a broad spectrum of applications. This work deals with the use of general purpose GPUs for performing computational fluid dynamics (CFD) computations. The paper discusses strategies and findings on porting a large multifunctional CFD code to the GPU architecture. Within this framework, the most compute intensive segment of the software, the BiCGStab linear solver using additive Schwarz block preconditioners with point Jacobi iterative smoothing is optimized for the GPU platform using various techniques in CUDA Fortran. Representative turbulent channel and pipe flow are investigated for validation and benchmarking purposes. Both single and double precision calculations are highlighted. For a modest single block grid of 64 × 64 × 64, the turbulent channel flow computations showed a speedup of about eightfold in double precision and more than 13-fold for single precision on the NVIDIA Tesla GPU over a serial run on an Intel central processing unit (CPU). For the pipe flow consisting of 1.78 × 106 grid cells distributed over 36 mesh blocks, the gains were more modest at 4.5 and 6.5 for double and single precision, respectively.

Download Full-text

Main helicopter rotor trimming using computational fluid dynamics method in forward flight

Proceedings of the Institution of Mechanical Engineers Part G Journal of Aerospace Engineering ◽

10.1177/0954410016673394 ◽

2016 ◽

Vol 232 (1) ◽

pp. 169-179 ◽

Cited By ~ 1

Author(s):

Yimin Ma ◽

Ming Chen ◽

Qiang Wang ◽

Fang Wang

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Main Rotor ◽

Overset Grid ◽

Forward Flight ◽

Time Step ◽

Pitch Motion ◽

Moment Coefficient ◽

Pitch Moment ◽

Dynamics Method

In this paper, a computational fluid dynamics trimming method is proposed and compared with wind tunnel experiment and the blade element method. The NASA’s generic ROBIN helicopter model is adopted for transient simulations to obtain the final main rotor trimming conditions. Totally three steps were applied to the computational fluid dynamics method. The first step is associated with no cyclic pitch motion, the second is regarding pure longitudinal cyclic pitch motion and the last is concerning with pure lateral cyclic pitch motion. At the same time, a simple linear equation system between the roll and pitching moment was established to get the final longitudinal and lateral cyclic pitch angles for the main rotor through the above three steps. An overset grid approach was used where the volume around each blade was modeled in an individual overset grid region. The rotor rotation was resolved with three degrees per time-step. Turbulence was modeled with the well-known SST K-omega model with second-order convection. The helicopter was in straight forward flight with an advance ratio of [Formula: see text]. Three sources of stick angles, which are also called rotor trimming angles, were shown and compared with each other. And the corresponding results were also plotted with a type of history plot in the computational fluid dynamics condition. In the simulations, the results became quasi periodic after about 1.5 rotations and four rotor rotations were simulated for each case. The pitch moment coefficient and roll moment coefficient were all trimmed to about zero by the computational fluid dynamics trimming method while moments were not removed thoroughly in the other two source conditions.

Download Full-text