Numerical investigation of two-phase secondary Kelvin–Helmholtz instability

Instability of the interface between two immiscible fluids representing the so-called Kelvin–Helmholtz instability problem is studied using smoothed particle hydrodynamics method. Interfacial tension is included, and the fluids are assumed to be inviscid. The time evolution of interfaces is obtained for two low Richardson numbers [Formula: see text] and [Formula: see text] while Bond number varies between zero and infinity. This study focuses on the effect of Bond and Richardson numbers on secondary instability of a two-dimensional shear layer. A brief theoretical discussion is given concerning the linear early time regime followed by numerical investigation of the growth of secondary waves on the main billow. Results show that for [Formula: see text], at all Bond numbers, secondary instabilities start in the early times after a perturbation is imposed, but they grow only for Bond numbers greater than 1. For [Formula: see text], however, secondary instabilities appear only at Bond numbers greater than 10. Finally, based on numerical simulations and using an energy budget analysis involving interfacial potential energy, a quantitative measure is given for the intensity of secondary instabilities using interfacial surface area.

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Effect of Rheological Properties of Yield Pseudoplastic Fluids on Slugs Characteristics in an Upward Vertical Pipe: Experiments and Modeling

Volume 11: Petroleum Technology ◽

10.1115/omae2020-19082 ◽

2020 ◽

Author(s):

Abdalsalam Ihmoudah ◽

Mohamed M. Awad ◽

Mohammad Azizur Rahman ◽

Stephen D. Butt

Keyword(s):

Liquid Phase ◽

Rheological Properties ◽

Numerical Investigation ◽

Two Phase Flow ◽

Immiscible Fluids ◽

Newtonian Fluids ◽

Phase Flow ◽

Vertical Pipe ◽

Two Phase ◽

Pseudoplastic Fluids

Abstract Two-phase flow of gas/yield Pseudoplastic fluids can be found in different industrial applications like the chemical processes, oil industry, and petroleum transport in pipelines. In this study, experimental and numerical investigation of the influence of Rheological properties of non-Newtonians fluids in two-phase flow (gas/yield Pseudoplastic fluids) on slug characteristics in an upward vertical flow were performed. Different concentrations of Xanthan gum solutions (0.05%, 0.10%, and 0.15%, by w/w), which are referred to as non-Newtonian, yield Pseudoplastic behavior used as the working liquids and air as a gas. The experiments were conducted in an open-loop re-circulating system has a total length of 65 m to ensure phase mixing, and authorize flow regime patterns to develop. The vertical pipe has a diameter of 76.3 mm. API-compliant 8-speed rotational viscometer model 800 was used to measure the rheological properties of non-Newtonian fluids. Flow visualization and recording videos were achieved by A high-speed camera to a comparison between behavior of Newtonian and non-Newtonian fluids in the two-phase model. Pressure transducers used to measure high-response pressure. Computational fluid dynamics software (ANSYS fluent 2019 R3) was used for the numerical investigation. The volume of fluid (VOF) model has been chosen for tracking immiscible fluids. CFD simulation results compared to the experimental data. The slug behavior and shape were noticed to be affected by changing the rheological properties of the liquid phase. with increasing XG concentration at the same operations conditions, we found that non-uniform and random distribution of small bubbles due to the effective viscous force of a liquid phase.

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Experimental and Numerical Investigation of Gas-Liquid Metal Two-Phase Flow Pumping

International Journal of Thermofluids ◽

10.1016/j.ijft.2021.100092 ◽

2021 ◽

pp. 100092

Author(s):

Josh Rosettani ◽

Wael Ahmed ◽

Philip Geddis ◽

Lijun Wu ◽

Bruce Clements

Keyword(s):

Liquid Metal ◽

Numerical Investigation ◽

Two Phase Flow ◽

Phase Flow ◽

Two Phase

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Numerical investigation of swirling flow and heat transfer of a nanofluid in a tube with helical ribs using a two-phase model

Journal of Thermal Analysis and Calorimetry ◽

10.1007/s10973-021-10661-1 ◽

2021 ◽

Author(s):

Roohollah Hosseini Monfared ◽

Mohammadreza Niknejadi ◽

Davood Toghraie ◽

Pouya Barnoon

Keyword(s):

Heat Transfer ◽

Numerical Investigation ◽

Swirling Flow ◽

Phase Model ◽

Two Phase ◽

Flow And Heat Transfer

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Depth-Integrated Two-Phase Modeling of Two Real Cases: A Comparison between r.avaflow and GeoFlow-SPH Codes

Applied Sciences ◽

10.3390/app11125751 ◽

2021 ◽

Vol 11 (12) ◽

pp. 5751

Author(s):

Seyed Ali Mousavi Tayebi ◽

Saeid Moussavi Tayyebi ◽

Manuel Pastor

Keyword(s):

Rock Avalanche ◽

Two Phase ◽

Simulation Code ◽

Simulation Tools ◽

Mesh Free ◽

Particle Hydrodynamics ◽

Landslide Evolution ◽

Smoothed Particle ◽

Hazard And Risk ◽

Comparison Of The Results

Due to the growing populations in areas at high risk of natural disasters, hazard and risk assessments of landslides have attracted significant attention from researchers worldwide. In order to assess potential risks and design possible countermeasures, it is necessary to have a better understanding of this phenomenon and its mechanism. As a result, the prediction of landslide evolution using continuum dynamic modeling implemented in advanced simulation tools is becoming more important. We analyzed a depth-integrated, two-phase model implemented in two different sets of code to stimulate rapid landslides, such as debris flows and rock avalanches. The first set of code, r.avaflow, represents a GIS-based computational framework and employs the NOC-TVD numerical scheme. The second set of code, GeoFlow-SPH, is based on the mesh-free numerical method of smoothed particle hydrodynamics (SPH) with the capability of describing pore pressure’s evolution along the vertical distribution of flowing mass. Two real cases of an Acheron rock avalanche and Sham Tseng San Tsuen debris flow were used with the best fit values of geotechnical parameters obtained in the prior modeling to investigate the capabilities of the sets of code. Comparison of the results evidenced that both sets of code were capable of properly reproducing the run-out distance, deposition thickness, and deposition shape in the benchmark exercises. However, the values of maximum propagation velocities and thickness were considerably different, suggesting that using more than one set of simulation code allows us to predict more accurately the possible scenarios and design more effective countermeasures.

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Numerical investigation of anguilliform locomotion by the SPH method

International Journal of Numerical Methods for Heat &amp Fluid Flow ◽

10.1108/hff-05-2019-0391 ◽

2019 ◽

Vol 30 (1) ◽

pp. 328-346 ◽

Cited By ~ 5

Author(s):

Amin Rahmat ◽

Hossein Nasiri ◽

Marjan Goodarzi ◽

Ehsan Heidaryan

Keyword(s):

Drag Coefficient ◽

Numerical Investigation ◽

Sph Method ◽

Content Type ◽

Aquatic Locomotion ◽

Wide Range ◽

Particle Hydrodynamics ◽

Dummy Particles ◽

Smoothed Particle ◽

Sph Algorithm

Purpose This paper aims to introduce a numerical investigation of aquatic locomotion using the smoothed particle hydrodynamics (SPH) method. Design/methodology/approach To model this problem, a simple improved SPH algorithm is presented that can handle complex geometries using updatable dummy particles. The computational code is validated by solving the flow over a two-dimensional cylinder and comparing its drag coefficient for two different Reynolds numbers with those in the literature. Findings Additionally, the drag coefficient and vortices created behind the aquatic swimmer are quantitatively and qualitatively compared with available credential data. Afterward, the flow over an aquatic swimmer is simulated for a wide range of Reynolds and Strouhal numbers, as well as for the amplitude envelope. Moreover, comprehensive discussions on drag coefficient and vorticity patterns behind the aquatic are made. Originality/value It is found that by increasing both Reynolds and Strouhal numbers separately, the anguilliform motion approaches the self-propulsion condition; however, the vortices show different pattern with these increments.

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