Numerical Modeling of Wind around Buildings of Different Heights

2015 ◽  
Vol 789-790 ◽  
pp. 1129-1133
Author(s):  
Ahmed M.A. Sattar ◽  
Mohamed Elhakeem
Keyword(s):  
Numerical Modeling ◽  
Standard Deviation ◽  
Flow Pattern ◽  
Numerical Study ◽  
Tall Buildings ◽  
Turbulence Level ◽  
3D Flow ◽  
Wind Environment ◽  
Velocity Magnitude

This paper presents a numerical study to simulate airflow around an array of buildings with different heights. The simulation showed a complex 3D flow pattern around the buildings. The velocity and standard deviation around the short buildings increased by about 30% compared to the same arrangement with buildings of the same height. Thus, the existence of the tall buildings increased the turbulence level and velocity magnitude around the short buildings. This suggests that the proposed buildings arrangement and spacing were effective in improving the wind environment around the buildings.

Investigation of Wind around Buildings of Different Heights Using an Environmental Wind Tunnel

2015 ◽  
Vol 789-790 ◽  
pp. 1114-1118 ◽  
Author(s):  
Mohamed Elhakeem ◽  
Ahmed M.A. Sattar
Keyword(s):  
Standard Deviation ◽  
Wind Tunnel ◽  
Tall Buildings ◽  
Physical Models ◽  
Turbulence Level ◽  
Wind Environment ◽  
Airflow Pattern ◽  
Airflow Field

This study presents experiments conducted in an environmental wind tunnel using physical models to quantify the airflow field around array of buildings of two different heights. A complex airflow pattern was developed around the buildings. In addition, the tall buildings increased the turbulence level around the short buildings. Combining short and tall buildings increased the spatially averaged velocity and standard deviation around the short buildings by 25% compared to the velocity and standard deviation around buildings of the same height. Thus, the proposed buildings arrangement and spacing proved to be effective in improving the wind environment around the buildings.

Karakteristik aliran dua fase pada saluran ekspansi tiba-tiba

2018 ◽  
Vol 11 (1) ◽  
pp. 7
Author(s):  
Latif Ngudi Wibawanto ◽  
Budi Santoso ◽  
Wibawa Endra Juwana
Keyword(s):  
Standard Deviation ◽  
Flow Pattern ◽  
Flow Characteristic ◽  
Homogeneous Model ◽  
Flow Equation ◽  
Pressure Recovery ◽  
Sudden Expansion ◽  
Air Velocity ◽  
Model Flow ◽  
Two Phases

This research was conducted to find out the flow characteristic of two phases through the channel with sudden expansion in the form of change of flow pattern and pressure recovery. The test was carried out with variation of superficial velocity of water 0.2-1.3 m / s and superficial air velocity of 0.2-1.9 m / s resulting in pattern of three flow patterns ie bubble, plug, and slug. The expansion channel resulted in some changes to the flow pattern that originally plugs in the upstream channel into bubble in the downstream channel and the slug becomes plug. Pressure recovery experimental results compared with the homogeneous model flow equation and Wadle correlation, both correlations have predictions with standard deviation values of 0.32 and 0.43.

Arriving at the Optimum Overlap Ratio for an Elliptical-Bladed Savonius Rotor

2017 ◽  
Author(s):  
Nur Alom ◽  
Ujjwal K. Saha
Keyword(s):  
Numerical Study ◽  
Superior Performance ◽  
Navier Stokes ◽  
Speed Ratio ◽  
Small Scale ◽  
Efficient Manner ◽  
Ansys Fluent ◽  
Savonius Rotor ◽  
Velocity Magnitude ◽  
Overlap Ratio

The Savonius rotor appears to be particularly promising for the small-scale applications because of its design simplicity, good starting ability, and insensitivity to wind directions. There has been a growing interest in recent times to harness wind energy in an efficient manner by developing newer blade profiles of Savonius rotor. The overlap ratio (OR), one of the important geometric parameters, plays a crucial role in the turbine performance. In a recent study, an elliptical blade profile with a sectional cut angle (θ) of 47.5° has demonstrated its superior performance when set at an OR = 0.20. However, this value of OR is ideal for a semicircular profile, and therefore, requires further investigation to arrive at the optimum overlap ratio for the elliptical profile. In view of this, the present study attempts to make a systemic numerical study to arrive at the optimum OR of the elliptical profile having sectional cut angle, θ = 47.5°. The 2D unsteady simulation is carried out around the elliptical profile considering various overlap ratios in the range of 0.0 to 0.30. The continuity, unsteady Reynolds Averaged Navier-Stokes (URANS) equations and two equation eddy viscosity SST (Shear Stress transport) k-ω model are solved by using the commercial finite volume method (FVM) based solver ANSYS Fluent. The torque and power coefficients are calculated as a function of tip speed ratio (TSR) and at rotating conditions. The total pressure, velocity magnitude and turbulence intensity contours are obtained and analyzed to arrive at the intended objective. The numerical simulation demonstrates an improved performance of the elliptical profile at an OR = 0.15.

Investigation of Flow in a Steam Turbine Exhaust Hood With/Without Turbine Exit Conditions Simulated

2001 ◽  
Author(s):  
Jianjun Liu ◽  
Yongqiang Cui ◽  
Hongde Jiang
Keyword(s):  
Flow Pattern ◽  
Static Pressure ◽  
Navier Stokes ◽  
Steam Turbines ◽  
Exhaust Hood ◽  
Flow Conditions ◽  
3D Flow ◽  
Typical Design ◽  
Turbine Exhaust ◽  
Good Agreement

Experimental and numerical investigations for the flow in an exhaust hood model of large steam turbines have been carried out in order to understand the complex 3D flow pattern existing in the hood and also to validate the CFD solver. The model is a typical design for 300/600 MW steam turbines currently in operation. Static pressure at the diffuser tip and hub endwalls and at hood outer casing is measured and nonuniform circumferential distributions of static pressure are noticed. Velocity field at the model exit is measured and compared with the numerical prediction. The multigrid multiblock 3D Navier-Stokes solver used for the simulations is based upon the TVD Lax-Wendroff scheme and the Baldwin-Lomax turbulence model. Good agreement between numerical results and experimental data is demonstrated. It is found that the flow pattern and hood performance are very different with or without the turbine exit flow conditions simulated.

Structural behaviour of water sloshing damper with embossments subject to random excitation

2004 ◽  
Vol 31 (1) ◽  
pp. 120-132 ◽  
Author(s):  
Young-Kyu Ju
Keyword(s):  
Standard Deviation ◽  
Vibration Control ◽  
Structural Model ◽  
Structural Characteristics ◽  
Damping Ratio ◽  
Tall Buildings ◽  
Random Excitation ◽  
Water Tank ◽  
Structural Behaviour ◽  
Peak Displacement

To improve the serviceability of tall buildings, several types of vibration control systems have been developed. The tuned liquid damper (TLD) has advantages, such as simple adjustment of natural frequency, easy installation, and low maintenance. Since water tanks at the top of tall buildings can be directly modeled as a TLD system, it is more practical than any other vibration control system in Korea. Since most of the tanks in Korea have embossments on the wall, the structural characteristics are different from those of tanks used in other countries. As the damping ratio of the TLD depends on several factors, such as the magnitude and frequency of applied load, the shape of the tank, wall roughness, and so forth, it is difficult to evaluate the control performance of the tank exactly. In this study, the characteristics of the water sloshing damper with embossments (WSDE) are evaluated and the equation for equivalent damping ratio is proposed. To clarify the damping effect of a high-rise building with a damping device subject to random excitation, an experiment of a coupled structural model with a water tank was conducted. The parameters were mass ratio of water to model structure, number of wire screens, and shape factor of the water tank. The peak displacement, acceleration response, and standard deviation of the experimental results are analyzed. The coupled structural model with a water tank shows lower maximum and standard deviation responses than those of the structural model alone.Key words: water sloshing damper with embossment, vibration control, structural test, tall buildings.

Numerical study of a turbulent separation bubble with sweep

2019 ◽  
Vol 880 ◽  
pp. 684-706
Author(s):  
G. N. Coleman ◽  
C. L. Rumsey ◽  
P. R. Spalart
Keyword(s):  
Pressure Gradient ◽  
Numerical Study ◽  
Separation Bubble ◽  
Laminar Flows ◽  
Swept Wing ◽  
Mean Velocity ◽  
Independence Principle ◽  
Velocity Magnitude ◽  
Turbulent Separation ◽  
Swept Wings

Direct numerical simulation (DNS) is used to study a separated and rapidly reattached turbulent boundary layer over an idealized $35^{\circ }$ infinite swept wing. The separation and reattachment are induced by a transpiration profile at fixed distance above the layer, with the pressure gradient applied to a well-defined, fully developed, zero-pressure-gradient (ZPG) collateral state. To isolate the influence of the sweep, results are compared with one of our earlier DNS of an unswept flow, with the same chordwise transpiration distribution and appropriate upstream momentum thickness. The independence principle (IP) traditionally proposed for swept wings, which is exact for laminar flows, is found to be close to valid in some regions (bridging the separation/reattachment zone) and to fail in others (in the ZPG layers upstream and downstream of the separation). This is assessed primarily through the skin friction and integral thicknesses. The regions in which the IP is approximately valid correspond to regions of diminished Reynolds-stress divergence, compared to the pressure-gradient magnitude. The mean-velocity profiles exhibit significant skewing as the flow develops, while the velocity magnitude departs only slightly from the ZPG logarithmic profile, even above the separation zone. Implications for Reynolds-averaged turbulence modelling are discussed.

Sign in / Sign up

Export Citation Format

Share Document