Flow around a cube for Reynolds numbers between 500 and 55,000

Khan, Majid Hassan; Sooraj, P.; Sharma, Atul; Agrawal, Amit

doi:10.1016/j.expthermflusci.2017.12.013

Cited by 32 publications

(13 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Decreasing the order of advection scheme from fifth to third also increases the numerical diffusion; however, the positions of the mean-flow features differ by less than 10%, except for the recirculation length (refer to s/m in Table 3). To our knowledge, there are no previous studies that assessed the impact of advection schemes to this canonical flow, but it was found that the impact of decreasing the order of numerical accuracy revealed in this study is very similar to the change of the flow pattern with decreasing Re (Khan et al 2018). For example, the reattachment length and the magnitude of the reverse flow on the lee side of the building gradually increase with decreasing Re (Khan et al 2018), similar to the impact of decreasing the order of advection scheme shown in Fig.…”

Section: Stagnationsupporting

confidence: 64%

“…The fundamental understanding of flow structures over urban topography has primarily been built on laboratory experiments and direct numerical simulations (DNSs) of flow around isolated surface-mounted cubic buildings, immersed in shear-driven turbulent flow at Reynolds numbers of O(10 3 -10 4 ) (e.g., Martinuzzi and Tropea 1993;Meinders and Hanjalić 1999;Yakhot et al 2006;Diaz-Daniel et al 2017;Khan et al 2018;and references therein). Despite the simple building geometry, the measurements and DNS results with such configuration have revealed characteristic features of flow response to buildings, including flow separations in the upstream and front corners of building's top and lateral faces, flow recirculation and reattachment, as well as unsteady vortex shedding in the wake region.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Large-Eddy Simulations of Stability-Varying Atmospheric Boundary Layer Flow over Isolated Buildings

Shin

Muñoz‐Esparza

Sauer

et al. 2021

Journal of the Atmospheric Sciences

View full text Add to dashboard Cite

This study explores the response of flow around isolated cuboid buildings to variations in the incoming turbulence arising from changes in atmospheric boundary layer (ABL) stability using a building-resolving large-eddy simulation (LES) technique with explicit representation of building effects through an immersed body force method. An extensive suite of LES for a neutral ABL with different model resolution and advection scheme configurations reveals that at least 6, 12, and 24 grid points per building side are required in order to resolve building-induced vortex shedding, mean-flow features, and turbulence statistics, respectively, with an advection scheme of a minimum of third-order. Using model resolutions that meet this requirement, 21 building-resolving simulations are performed under varying atmospheric stability conditions, from weakly stable to convective ABLs, and for different building sizes (H), resulting in LABL/H ≈ 0.1 – 10, where LABL is the integral length scale of the incoming ABL turbulence. The building-induced flow features observed in the canonical neutral ABL simulation, e.g., the upstream horseshoe vortex and the downstream arch vortex, gradually weaken with increasing surface-driven convective instability due to the enhancement of background turbulent mixing. As a result, two local turbulence kinetic energy peaks on the lateral side of the building in non-convective cases are merged into a single peak in strong convective cases. By considering the ABL turbulence scale and building size altogether, it is shown that the building impact decreases with increasing LABL/H, as coherent turbulent structures in the ABL become more dominant over a building-induced flow response for LABL/H > 1.

show abstract

Section: Stagnationsupporting

confidence: 64%

Section: Introductionmentioning

confidence: 99%

Large-Eddy Simulations of Stability-Varying Atmospheric Boundary Layer Flow over Isolated Buildings

Shin

Muñoz‐Esparza

Sauer

et al. 2021

Journal of the Atmospheric Sciences

View full text Add to dashboard Cite

show abstract

“…The percentage of rejected vectors from each frame is less than 4%. Additional details about our water tunnel and PIV facilities can be found in Khan et al [12] and Sooraj et al [35].…”

Section: Methodsmentioning

confidence: 99%

Passive flow control mechanism in a bio-inspired corrugated hydrofoil

Sooraj

Agrawal

2019

SN Appl. Sci.

Self Cite

View full text Add to dashboard Cite

Corrugated hydrofoils are lately getting attention because of their superior aerodynamic performance compared to engineered hydrofoils at low Reynolds numbers (Re). A particle image velocimetry (PIV) based study on corrugated hydrofoil is conducted here to understand the flow dynamics around it at ultralow Reynolds numbers (Re = 280-11,700). Seven different angles of attack (α) are considered in this study ranging from − 15° to 15°. Load cell measurements are undertaken to obtain the force coefficients and further these are compared with the results obtained from PIV data using wake survey method. The wake velocity profiles are examined to understand the variation in force coefficients in a better way. Vortices are found to be trapped in the valley of the corrugations. The lift coefficient increases as the number of vortices increases on the top (suction) surface. A temporal analysis of the data shows that the partially merged co-rotating vortices give higher lift as compared to the fully merged vortices. The maximum aerodynamic performance is obtained at − 5° angle of attack for Re = 6760. The asymmetry in the geometry combined with asymmetry in the flow helps create relatively high lift for a corrugated wing. The performance of positive and negative angles of attack are compared and it is found that the fluctuation in lift coefficient is comparatively higher. It is hypothesized that the merging of trapped vortices with each other gives the effect of fluid roller bearings; this fluid roller bearing produces a travelling wave, which avoids the formation of boundary layer, thereby leading to high gliding ratio. These detailed results, covering the entire Reynolds number and angle of attack range of dragonfly flight, provide useful insights into the secret of dragonfly flight which will help in better design of micro air vehicles.

show abstract

“…The use of a constant drag coefficient at Reynold’s numbers below 10,000, which is applicable to our experiments, is a somewhat crude approximation [47,48]. Nevertheless, we apply it in order to acquire a simple closed-form solution.…”

Section: Design and Operating Principlementioning

confidence: 99%

Capacitive Bio-Inspired Flow Sensing Cupula

Wissman

Sampath

Freeman

et al. 2019

Sensors

View full text Add to dashboard Cite

Submersible robotics have improved in efficiency and versatility by incorporating features found in aquatic life, ranging from thunniform kinematics to shark skin textures. To fully realize these benefits, sensor systems must be incorporated to aid in object detection and navigation through complex flows. Again, inspiration can be taken from biology, drawing on the lateral line sensor systems and neuromast structures found on fish. To maintain a truly soft-bodied robot, a man-made flow sensor must be developed that is entirely complaint, introducing no rigidity to the artificial “skin.” We present a capacitive cupula inspired by superficial neuromasts. Fabricated via lost wax methods and vacuum injection, our 5 mm tall device exhibits a sensitivity of 0.5 pF/mm (capacitance versus tip deflection) and consists of room temperature liquid metal plates embedded in a soft silicone body. In contrast to existing capacitive examples, our sensor incorporates the transducers into the cupula itself rather than at its base. We present a kinematic theory and energy-based approach to approximate capacitance versus flow, resulting in equations that are verified with a combination of experiments and COMSOL simulations.

show abstract

Flow around a cube for Reynolds numbers between 500 and 55,000

Cited by 32 publications

References 42 publications

Large-Eddy Simulations of Stability-Varying Atmospheric Boundary Layer Flow over Isolated Buildings

Large-Eddy Simulations of Stability-Varying Atmospheric Boundary Layer Flow over Isolated Buildings

Passive flow control mechanism in a bio-inspired corrugated hydrofoil

Capacitive Bio-Inspired Flow Sensing Cupula

Contact Info

Product

Resources

About