scholarly journals Role of Inflow Turbulence and Surrounding Buildings on Large Eddy Simulations of Urban Wind Energy

Energies ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 5208 ◽  
Author(s):  
Giulio Vita ◽  
Syeda Anam Hashmi ◽  
Simone Salvadori ◽  
Hassan Hemida ◽  
Charalampos Baniotopoulos
Keyword(s):  
Wind Energy ◽  
Geometric Model ◽  
Tall Buildings ◽  
Flow Patterns ◽  
Eddy Simulation ◽  
Turbulent Inflow ◽  
Positioning Strategy ◽  
Large Eddy ◽  
Inflow Turbulence ◽  
Mean Wind Speed

Predicting flow patterns that develop on the roof of high-rise buildings is critical for the development of urban wind energy. In particular, the performance and reliability of devices largely depends on the positioning strategy, a major unresolved challenge. This work aims at investigating the effect of variations in the turbulent inflow and the geometric model on the flow patterns that develop on the roof of tall buildings in the realistic configuration of the University of Birmingham’s campus in the United Kingdom (UK). Results confirm that the accuracy of Large Eddy Simulation (LES) predictions is only marginally affected by differences in the inflow mean wind speed and turbulence intensity, provided that turbulence is not absent. The effect of the presence of surrounding buildings is also investigated and found to be marginal to the results if the inflow is turbulent. The integral length scale is the parameter most affected by the turbulence characteristics of the inflow, while gustiness is only marginally influenced. This work will contribute to LES applications on the urban wind resource and their computational setup simplification.

Modeling of Effect of Inflow Turbulence Data on Large Eddy Simulation of Circular Cylinder Flows

2006 ◽  
Vol 129 (6) ◽  
pp. 780-790 ◽  
Author(s):  
M. Tutar ◽  
I. Celik ◽  
I. Yavuz
Keyword(s):  
Reynolds Number ◽  
Circular Cylinder ◽  
Large Eddy Simulation ◽  
Boundary Conditions ◽  
Wake Flow ◽  
Eddy Simulation ◽  
Turbulent Inflow ◽  
Large Eddy ◽  
Inflow Turbulence ◽  
Near Wall

A random flow generation (RFG) algorithm for a previously established large eddy simulation (LES) code is successfully incorporated into a finite element fluid flow solver to generate the required inflow/initial turbulence boundary conditions for the three-dimensional (3D) LES computations of viscous incompressible turbulent flow over a nominally two-dimensional (2D) circular cylinder at Reynolds number of 140,000. The effect of generated turbulent inflow boundary conditions on the near wake flow and the shear layer and on the prediction of integral flow parameters is studied based on long time average results. Because the near-wall region cannot be resolved for high Reynolds number flows, no-slip velocity boundary function is used, but wall effects are taken into consideration with a near-wall modeling methodology that comprises the no-slip function with a modified form of van Driest damping approach to reduce the subgrid length scale in the vicinity of the cylinder wall. Simulations are performed for a 2D and a 3D configuration, and the simulation results are compared to each other and to the experimental data for different turbulent inflow boundary conditions with varying degree of inflow turbulence to assess the functionality of the RFG algorithm for the present LES code and, hence, its influence on the vortex shedding mechanism and the resulting flow field predictions.

Flow patterns of vertical plane thermal buoyant jet in shallow water

2018 ◽  
Vol 32 (12n13) ◽  
pp. 1840041
Author(s):  
Li-Qing Zhao ◽  
Jian-Hong Sun ◽  
Yang Lu
Keyword(s):  
Flow Pattern ◽  
Vertical Plane ◽  
Free Water ◽  
Simulation Method ◽  
Boussinesq Approximation ◽  
Flow Patterns ◽  
Buoyant Jet ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Impinging Flow

A heated plane water jet impinging vertically onto free water surface has been numerically studied based on large eddy simulation method coupled with the volume of fluid approach. The Boussinesq approximation is adopted to simulate the effect of buoyancy. Results showed that there exist two flow patterns for the plane thermal buoyant jet, which are the stable impinging flow pattern and the flapping impinging flow pattern. Distinct temperature stratification can be found in the stable impinging flow pattern, while it disappears in the flapping impinging flow pattern.

Large Eddy Simulation of Laminar and Turbulent Shock/Boundary Layer Interactions in a Transonic Passage

2020 ◽  
Author(s):  
Stephan Priebe ◽  
Daniel Wilkin ◽  
Andy Breeze-Stringfellow ◽  
Giridhar Jothiprasad ◽  
Lawrence C. Cheung
Keyword(s):  
Boundary Layer ◽  
Large Eddy Simulation ◽  
Low Frequency ◽  
Boundary Layer Separation ◽  
Eddy Simulation ◽  
Turbulent Inflow ◽  
Wide Range ◽  
Large Eddy ◽  
Constant Radius ◽  
Structure Boundary

Abstract Shock/boundary layer interactions (SBLI) are a fundamental fluid mechanics problem relevant in a wide range of applications including transonic rotors in turbomachinery. This paper uses wall-resolved large eddy simulation (LES) to examine the interaction of normal shocks with laminar and turbulent inflow boundary layers in transonic flow. The calculations were performed using GENESIS, a high-order, unstructured LES solver. The geometry created for this study is a transonic passage with a convergent-divergent nozzle that expands the flow to the desired Mach number upstream of the shock and then introduces constant radius curvature to simulate local airfoil camber. The Mach numbers in the divergent section of the transonic passage simulate single stage commercial fan blades. The results predicted with the LES calculations show significant differences between laminar and turbulent SBLI in terms of shock structure, boundary layer separation and transition, and aerodynamic losses. For laminar flow into the shock, significant flow separation and low-frequency unsteadiness occur, while for turbulent flow into the shock, both the boundary layer loss and the low-frequency unsteadiness are reduced.

Large Eddy Simulation of Bypass Transition in Vane Passage With Freestream Turbulence

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
Yousef Kanani ◽  
Sumanta Acharya ◽  
Forrest Ames
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Large Eddy Simulation ◽  
Bypass Transition ◽  
Freestream Turbulence ◽  
Turbulent Spot ◽  
Suction Surface ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Inflow Turbulence

Abstract High Reynolds flow over a nozzle guide-vane with elevated inflow turbulence was simulated using wall-resolved large eddy simulation (LES). The simulations were undertaken at an exit Reynolds number of 0.5 × 106 and inflow turbulence levels of 0.7% and 7.9% and for uniform heat-flux boundary conditions corresponding to the measurements of Varty and Ames (2016, “Experimental Heat Transfer Distributions Over an Aft Loaded Vane With a Large Leading Edge at Very High Turbulence Levels,” ASME Paper No. IMECE2016-67029). The predicted heat transfer distribution over the vane is in excellent agreement with measurements. At higher freestream turbulence, the simulations accurately capture the laminar heat transfer augmentation on the pressure surface and the transition to turbulence on the suction surface. The bypass transition on the suction surface is preceded by boundary layer streaks formed under the external forcing of freestream disturbances which breakdown to turbulence through inner-mode secondary instabilities. Underneath the locally formed turbulent spot, heat transfer coefficient spikes and generally follows the same pattern as the turbulent spot. The details of the flow and temperature fields on the suction side are characterized, and first- and second-order statistics are documented. The turbulent Prandtl number in the boundary layer is generally in the range of 0.7–1, but decays rapidly near the wall.

Sign in / Sign up

Export Citation Format

Share Document