Numerical Simulations of Flow Around Wall-Mounted Square and Trapezoidal Structures at High Reynolds Numbers

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Martin Andersen ◽  
Guang Yin ◽  
Muk Chen Ong
Keyword(s):  
Turbulence Model ◽  
Reynolds Numbers ◽  
Navier Stokes ◽  
Freestream Velocity ◽  
High Reynolds Numbers ◽  
Sst Turbulence Model ◽  
Layer Flow ◽  
High Reynolds ◽  
Two Sides ◽  
Good Agreement

Abstract In the present study, flow around symmetric trapezoidal wall-mounted structures with different slope angles of the two sides subjected to a boundary layer flow at Reynolds numbers of 1.19 × 105 and 1 × 106 (based on the height of the structures and the freestream velocity) is investigated using two-dimensional (2D) Reynolds-averaged Navier–Stokes (RANS) equations combined with the k − ω shear stress transport (SST) turbulence model. It is found that the drag coefficient of the wall-mounted square structures using the k − ω SST turbulence model is in good agreement with the available published experimental data. The effects of slope angles of the two sides on the hydrodynamic quantities and the flow fields around the structures have been investigated.

scholarly journals Prediction of the Propeller Performance at Different Reynolds Number Regimes with RANS

2021 ◽  
Vol 9 (10) ◽  
pp. 1115
Author(s):  
João Baltazar ◽  
Douwe Rijpkema ◽  
José Falcão de Campos
Keyword(s):  
Reynolds Number ◽  
Turbulence Model ◽  
Scale Effects ◽  
Open Water ◽  
Reynolds Numbers ◽  
Navier Stokes ◽  
Transition Model ◽  
Sst Turbulence Model ◽  
Propeller Performance ◽  
Selection Of

In this study, a Reynolds averaged Navier-Stokes solver is used for prediction of the propeller performance in open-water conditions at different Reynolds numbers ranging from 104 to 107. The k−ω SST turbulence model and the γ−R˜eθt correlation-based transition model are utilised and results compared for a conventional marine propeller. First, the selection of the turbulence inlet quantities for different flow regimes is discussed. Then, an analysis of the iterative and discretisation errors is made. This work is followed by an investigation of the predicted propeller flow at variable Reynolds numbers. Finally, the propeller scale-effects and the influence of the turbulence and transition models on the performance prediction are discussed. The variation of the flow regime showed an increase in thrust and decrease in torque for increasing Reynolds number. From the comparison between the turbulence model and the transition model, different flow solutions are obtained for the Reynolds numbers between 105 and 106, affecting the scale-effects prediction.

Numerical Investigation of Flow Interference Effects in Fixed and Vibrating Tandem Square Columns Using Hybrid RANS-LES Models

2015 ◽  
Author(s):  
Harish Gopalan ◽  
Dominic Denver John Chandar ◽  
Narasimha Rao Pillamarri ◽  
Guan Mengzhao ◽  
Rajeev K. Jaiman ◽  
...  
Keyword(s):  
Solid Wall ◽  
Computational Cost ◽  
Reynolds Numbers ◽  
Navier Stokes ◽  
Arbitrary Lagrangian Eulerian ◽  
High Reynolds Numbers ◽  
Flow Past ◽  
Ale Methods ◽  
High Reynolds ◽  
Flow Interference

Investigation of flow past tandem and side-by-side circular and square columns is of interest in offshore engineering. Flow past fixed and vibrating circular columns has received a lot of focus in the literature. However, the studies focused on square columns, especially at high Reynolds numbers are very limited due to the computational cost of large eddy simulation (LES). Unsteady Reynolds-averaged Navier-Stokes (URANS) methods are limited by their accuracy, especially for tandem columns in the wake interference regime (spacing to diameter ratio: L=D ∼ 3:0). Hybrid URANS-LES models (URANS near the solid-wall and LES away from the wall) can overcome the drawbacks of the traditional URANS methods and can provide a reasonable prediction of the flow physics at a fraction of the cost of LES without significantly sacrificing numerical accuracy. Arbitrary Lagrangian-Eulerian (ALE) methods fails when vibrating tandem bodies are in close proximity to each other or vibrate at high reduced velocities. Remeshing the domain can be expensive, especially at high Reynolds numbers (Re). Alternate strategies are necessary to efficiently simulation this problems. This study proposes the use of a non-linear URANS-LES model, coupled with an overset mesh method (for vibrating columns), for studying flow past tandem square columns. Simulations are performed at sub-critical Re to match the experimental Re. The initial results are encouraging for further investigation of fixed and vibrating tandem square column flow interference at high Reynolds numbers.

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