3D Numerical Studies on Variable Thrust Propulsion of Rhinoceros Beetle at Creeping Flow Conditions

2017 ◽  
Author(s):  
Arunkumar B ◽  
Vignesh Saravanan ◽  
Edison Edward A ◽  
Pavithra Murugesh ◽  
VR Sanal Kumar ◽  
...  
Keyword(s):  
Creeping Flow ◽  
Flow Conditions ◽  
Rhinoceros Beetle ◽  
Numerical Studies

Numerical Studies on Trapped-Vortex Concepts for Stable Combustion

1998 ◽  
Vol 120 (1) ◽  
pp. 60-68 ◽  
Author(s):  
V. R. Katta ◽  
W. M. Roquemore
Keyword(s):  
Drag Coefficient ◽  
Reacting Flow ◽  
Flow Conditions ◽  
Third Order ◽  
Cold Flow ◽  
Flow Simulations ◽  
Numerical Studies ◽  
Dynamic Flows ◽  
Experimental Findings ◽  
Trapped Vortex

Spatially locked vortices in the cavities of a combustor aid in stabilizing the flames. On the other hand, these stationary vortices also restrict the entrainment of the main air into the cavity. For obtaining good performance characteristics in a trapped-vortex combustor, a sufficient amount of fuel and air must be injected directly into the cavity. This paper describes a numerical investigation performed to understand better the entrainment and residence-time characteristics of cavity flows for different cavity and spindle sizes. A third-order-accurate time-dependent Computational Fluid Dynamics with Chemistry (CFDC) code was used for simulating the dynamic flows associated with forebody-spindle-disk geometry. It was found from the nonreacting flow simulations that the drag coefficient decreases with cavity length and that an optimum size exists for achieving a minimum value. These observations support the earlier experimental findings of Little and Whipkey (1979). At the optimum disk location, the vortices inside the cavity and behind the disk are spatially locked. It was also found that for cavity sizes slightly larger than the optimum, even though the vortices are spatially locked, the drag coefficient increases significantly. Entrainment of the main flow was observed to be greater into the smaller-than-optimum cavities. The reacting-flow calculations indicate that the dynamic vortices developed inside the cavity with the injection of fuel and air do not shed, even though the cavity size was determined based on cold-flow conditions.

A Note on the Creeping Flow of a Viscous Liquid in the Region Between a Horizontal Plate and Moving Scraper

1971 ◽  
Vol 38 (4) ◽  
pp. 1056-1057
Author(s):  
J. R. Jones ◽  
T. S. Walters
Keyword(s):  
Viscous Liquid ◽  
Creeping Flow ◽  
Horizontal Plate ◽  
Flow Conditions ◽  
General Flow

The problem of flow of a viscous liquid in the region between a solid horizontal plate and a moving scraper is considered. The work of Rice and McAlister is extended to cover general flow conditions across the boundary.

A 3D DLM/FD method for simulating the motion of spheres and ellipsoids under creeping flow conditions

2018 ◽  
Vol 352 ◽  
pp. 410-425 ◽  
Author(s):  
Tsorng-Whay Pan ◽  
Aixia Guo ◽  
Shang-Huan Chiu ◽  
Roland Glowinski
Keyword(s):  
Creeping Flow ◽  
Flow Conditions

Creeping Flow Through an Axisymmetric Sudden Contraction or Expansion

2001 ◽  
Vol 124 (1) ◽  
pp. 273-278 ◽  
Author(s):  
Sourith Sisavath ◽  
Xudong Jing ◽  
Chris C. Pain ◽  
Robert W. Zimmerman
Keyword(s):  
Pressure Drop ◽  
Expansion Ratio ◽  
Excess Pressure ◽  
Creeping Flow ◽  
Numerical Studies ◽  
Equivalent Length ◽  
Sudden Contraction ◽  
Circular Orifice ◽  
Flow Through ◽  
Infinite Wall

Creeping flow through a sudden contraction/expansion in an axisymmetric pipe is studied. Sampson’s solution for flow through a circular orifice in an infinite wall is used to derive an approximation for the excess pressure drop due to a sudden contraction/expansion in a pipe with a finite expansion ratio. The accuracy of this approximation obtained is verified by comparing its results to finite-element simulations and other previous numerical studies. The result can also be extended to a thin annular obstacle in a circular pipe. The “equivalent length” corresponding to the excess pressure drop is found to be barely half the radius of the smaller tube.

Non-local continuum modelling of steady, dense granular heap flows

2017 ◽  
Vol 831 ◽  
pp. 212-227 ◽  
Author(s):  
Daren Liu ◽  
David L. Henann
Keyword(s):  
Flow Rate ◽  
Creeping Flow ◽  
Decay Length ◽  
Flow Conditions ◽  
Rate Dependent ◽  
Continuum Modelling ◽  
Rapid Flow ◽  
Dense Granular Flow ◽  
Non Local ◽  
Side Walls

Dense granular heap flows are common in nature, such as during avalanches and landslides, as well as in industrial flows. In granular heap flows, rapid flow is localized near the free surface with the thickness of the rapidly flowing layer dependent on the overall flow rate. In the region deep beneath the surface, exponentially decaying creeping flow dominates with characteristic decay length depending only on the geometry and not the overall flow rate. Existing continuum models for dense granular flow based upon local constitutive equations are not able to simultaneously predict both of these experimentally observed features – failing to even predict the existence of creeping flow beneath the surface. In this work, we apply a scale-dependent continuum approach – the non-local granular fluidity model – to steady, dense granular flows on a heap between two smooth, frictional side walls. We show that the model captures the salient features of both the flow-rate-dependent, rapidly flowing surface layer and the flow-rate-independent, slowly creeping bulk under steady flow conditions.

Convective diffusion to a slowly rotating spherical electrode; The effect of axial diffusion in the bulk liquid for Re 10

1985 ◽  
Vol 50 (4) ◽  
pp. 806-827
Author(s):  
Pavel Mitschka ◽  
Ondřej Wein
Keyword(s):  
Mathematical Model ◽  
Convective Diffusion ◽  
Creeping Flow ◽  
Bulk Liquid ◽  
Axially Symmetric ◽  
Flow Conditions ◽  
Transfer Coefficients ◽  
Axial Diffusion ◽  
Spherical Electrode ◽  
Method Of Solution

A complete mathematical model has been solved of the steady axially symmetric convective diffusion toward the surface of a spherical electrode of radius R rotating at an angular velocity Ω under the creeping flow conditions Re ≡ ΩR2ρ/η < 10 and Pe ≡ Ω2R4ρ/(12Dη) > 10 by the method of singular perturbations. For Pe > 300 the effect of axial diffusion has been found entirely negligible; for 10 < Pe < 300 it causes an increase of local transfer coefficients by 1-10%. For Pe < 10 the applied asymptotic method of solution, assuming Pe >> 1 is no longer applicable.

scholarly journals Experimental and numerical studies of sound generated by cavities

2019 ◽  
Vol 137 ◽  
pp. 01011
Author(s):  
Sebastian Rulik ◽  
Włodzimierz Wrόblewski ◽  
Mirosław Majkut ◽  
Michał Strozik ◽  
Krzysztof Rusin
Keyword(s):  
High Frequency ◽  
Measurement Techniques ◽  
Pressure Fluctuations ◽  
Three Dimensional ◽  
High Amplitude ◽  
Noise Generation ◽  
Flow Conditions ◽  
Numerical Studies ◽  
Wide Range ◽  
Specific Frequency

Cavities and gaps are an important element in the construction of many devices and machines, including energy sector applications. This type of flow is usually coupled with strong pressure fluctuations inside the cavity, which are emitted into the far field in the form of a sound wave responsible for the noise generation. This applies to both subsonic and supersonic flows. Pressure fluctuations often have the character of single tones of a specific frequency and high amplitude and their generation is associated with a vortex shedding formed directly above the inlet and its interaction with the walls of the cavity. The presented work include description of developed test stand and applied measurement techniques dedicated to the analysis of high frequency phenomena. In addition, the adopted numerical model will be described, including conducted two-dimensional and three-dimensional analysis. The developed models will be validated based on experimental measurements concerning wide range of flow conditions.

An Experimental Investigation of Flow Phenomena in a Multi-Stage Micro Tesla Valve

2021 ◽  
Author(s):  
Jan Raffel ◽  
Shadi Ansari ◽  
David S. Nobes
Keyword(s):  
Reynolds Number ◽  
Vortex Shedding ◽  
Flow Conditions ◽  
Numerical Studies ◽  
Multi Stage ◽  
Flow Phenomena ◽  
Potential Applications ◽  
Tesla Valve ◽  
Reynolds Number Flows ◽  
Unsteady Behavior

Abstract The Tesla-diode valve, with no moving parts, allows restricted flow in one direction. It has many potential applications in different industrial situations. Despite the application of the valve and the importance of the effect of flow phenomena on the Tesla valve's performance, very few studies have experimentally investigated the motion of flow within the Tesla valve. This study aims to contribute to this growing area of research on the performance of Tesla valves by demonstrating the flow phenomena and the flow conditions needed to be used in numerical studies. In this work, the effect of direction of the flow and Reynolds number on the flow phenomena generated in a Tesla-diode valve is studied. Particle shadowgraph velocimetry (PSV) is utilized to investigate and visualize the velocity field. The results of this study confirm some of the phenomena that has been observed using numerical simulations. It also highlights the flow phenomena leading to an increase in the diodicity by an increase in the number of Tesla loops in the valve. An important observation often ignored in numerical simulation is the presence of unsteady behavior and vortex shedding for higher Reynolds number flows.

Experimental and numerical studies of one-directional and bi-directional flow conditions across tube banks heat exchanger

2021 ◽  
pp. 101176
Author(s):  
Nurjannah Hasbullah ◽  
Fatimah Al Zahrah Mohd Saat ◽  
Fadhilah Shikh Anuar ◽  
Mohamad Firdaus Sukri ◽  
Patcharin Saechan
Keyword(s):  
Heat Exchanger ◽  
Flow Conditions ◽  
Directional Flow ◽  
Numerical Studies ◽  
Tube Banks
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