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navier-stokes-equations
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Details study on the kinematic characteristics of manta ray section in flapping motion and exploring its application in wave glider propulsion system
, Article Sustainable Energy Technologies and Assessments ; Volume 53 , 2022 ; 22131388 (ISSN) ; Safari, H ; Darbandi, M ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
It has always been a human challenge to inspire natural configurations and phenomena and benefit from their merits in improving the performances of man-made proposed aero/hydro vehicles. For example, the manta rays are known for their great swimming performances. To design and fabricate an underwater robot based on the manta ray geometry and its kinematic characteristics, it is important to initially study its hydrodynamic behavior and possibly arrive at some key design parameters, which can remarkably help to figure out an optimum geometry with high swimming performances. The main objective of this study is to focus on the merits of gliding motion inspired by the manta ray fish considering...
Numerical simulation of vortex-induced vibration of a smooth circular cylinder at the subcritical regime
, Article Proceedings of the Institution of Mechanical Engineers Part M: Journal of Engineering for the Maritime Environment ; Volume 236, Issue 4 , 2022 , Pages 916-937 ; 14750902 (ISSN) ; Nemati Kourabbasloo, N ; Mohtat, P ; Tanha, A ; Sharif University of Technology
SAGE Publications Ltd
2022
Abstract
The present paper focuses on the simulation of vortex-induced vibration (VIV) of a rigid, smooth circular cylinder with elastic supports subject to a cross-flow at the subcritical regime of Reynolds number, 30,000
Continuous submicron particle separation Via Vortex-Enhanced ionic concentration polarization: a numerical investigation
, Article Micromachines ; Volume 13, Issue 12 , 2022 ; 2072666X (ISSN) ; Amiri, H.A ; Collins, D.J ; Miansari, M ; Sharif University of Technology
MDPI
2022
Abstract
Separation and isolation of suspended submicron particles is fundamental to a wide range of applications, including desalination, chemical processing, and medical diagnostics. Ion concentration polarization (ICP), an electrokinetic phenomenon in micro-nano interfaces, has gained attention due to its unique ability to manipulate molecules or particles in suspension and solution. Less well understood, though, is the ability of this phenomenon to generate circulatory fluid flow, and how this enables and enhances continuous particle capture. Here, we perform a comprehensive study of a low-voltage ICP, demonstrating a new electrokinetic method for extracting submicron particles via flow-enhanced...
Investigation of flame structure and precessing vortex core instability of a gas turbine model combustor with different swirler configurations
, Article Physics of Fluids ; Volume 34, Issue 8 , 2022 ; 10706631 (ISSN) ; Asadi, B ; Beige, A. A ; Sharif University of Technology
American Institute of Physics Inc
2022
Abstract
Numerical simulation of a dual-swirl gas turbine model combustor is performed under cold and reacting flow conditions using a three-dimensional unsteady Reynolds-averaged Navier-Stokes approach. A multi-species chemical mechanism is used in this study for the analysis of the numerous radicals participating in the ignition process and the flame structure. The other objective of this study is to investigate the flow field under different injector configurations, including both co-rotating and counter-rotating swirler arrangements, different swirl intensities, and vane areas. A comparison of the results with experimental data shows that the predicted velocity and temperature profiles follow the...
A high-order nodal discontinuous Galerkin method for simulation of three-dimensional non-cavitating/cavitating flows
, Article Finite Elements in Analysis and Design ; Volume 200 , 2022 ; 0168874X (ISSN) ; Hejranfar, K ; Sharif University of Technology
Elsevier B.V
2022
Abstract
In this study, the nodal discontinuous Galerkin method is formulated in three-dimensions and applied to simulate three-dimensional non-cavitating/cavitating flows. For this aim, the three-dimensional preconditioned Navier-Stokes equations based on the artificial compressibility approach considering appropriate source terms to model cavitating phenomena are used. The spatial derivative terms in the resulting equations are discretized by utilizing the nodal discontinuous Galerkin method on tetrahedral elements and the derivative of the solution vector with respect to the artificial time is discretized by applying an explicit time integration method. An artificial viscosity method is formulated...
Application of numerical simulation to solid phase-microextraction for decreasing of extraction time of pyrene and phthalate esters on solid coatings
, Article Journal of Chromatography A ; Volume 1673 , 2022 ; 00219673 (ISSN) ; Jamshidian, M ; Habibi, S ; Sharif University of Technology
Elsevier B.V
2022
Abstract
Reynolds-Averaged Navier-Stokes (RANS) approach with the k-ε closure model is employed for the first time to simulate direct Solid-Phase Micro-Extraction (SPME) computationally. Simulations are performed by using COMSOL Multiphysics in order to examine methods to decrease the extraction time. Experiments are also conducted to support data obtained from the numerical framework. Di-n-Butyl Phthalate (DNBP) and etched steel wire are chosen as the analyte and the adsorbent, respectively. Stirring rate, fiber's location, stirrer magnet's size, and the method of sample rotation are examined to decrease the extraction time. In addition, the effects of adding a baffle to the vial and implementing a...
Plasma actuator effects on the flow physics of dynamic stall for a vertical axis wind turbine
, Article Physics of Fluids ; Volume 34, Issue 7 , 2022 ; 10706631 (ISSN) ; Ebrahimi, A ; Sharif University of Technology
American Institute of Physics Inc
2022
Abstract
Darrieus type vertical axis wind turbines have several advantages over other wind turbines for local electricity generation in urban environments. However, the main aerodynamic challenge is the negative impacts of the dynamic stall phenomenon on the turbine performance. This study numerically scrutinizes the effects of plasma actuators on the dynamic stall control and performance improvement of a Darrieus turbine. For this sake, unsteady Reynolds-averaged Navier-Stokes equations are solved using a pressure-based finite volume method. The Suzen-Hoang plasma actuator model is employed to calculate the body forces attributed to the plasma actuator. First, the dynamic stall characteristics of...
Nonlinear vibrations and stability of rotating cylindrical shells conveying annular fluid medium
, Article Thin-Walled Structures ; Volume 171 , 2022 ; 02638231 (ISSN) ; Firouz abadi, R. D ; Rahmanian, M ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
This study aims to investigate the nonlinear dynamic characteristics of annular cylinders coupled with a fluid medium to identify the effective parameters on stability margins at different rotation speeds. To achieve this, stability and nonlinear vibrations of rotating cylindrical shells containing incompressible annular fluid are considered. The fluid medium is bounded by a rigid external cylinder. Sanders–Koiter kinematic assumptions are utilized to determine the geometrically nonlinear structural equations of motion. These equations are then used to investigate finite amplitude vibrations of various fluid-loaded shells at different states. A penalty approach is introduced by using...
A hybrid model for simulation of fluid-structure interaction in water entry problems
, Article Physics of Fluids ; Volume 33, Issue 1 , 2021 ; 10706631 (ISSN) ; Rahbar Ranji, A ; Haddadpour, H ; Moghadas, H ; Sharif University of Technology
American Institute of Physics Inc
2021
Abstract
A hydroelastic hybrid model is developed to simulate the fluid-structure interaction in water entry problems using the partitioned approach. The interactions between a flat plate and the water are modeled by a hydroelastic model using explicit and implicit couplings. Both couplings are unstable due to numerical instability associated with the fluid added mass. To overcome the instability, an extended Wagner's model is combined with the hydroelastic model, and a hybrid model is developed. The extended Wagner's model is the extension of the classical Wagner's model that is used to estimate the fluid inertial, damping, and restoring forces of a flexible plate within the potential flow theory....
Numerical analysis of two-phase flow in heterogeneous porous media during pre-flush stage of matrix acidizing: Optimization by response surface methodology
, Article Physics of Fluids ; Volume 33, Issue 5 , 2021 ; 10706631 (ISSN) ; Rokhforouz, M. R ; Kazemi, A ; Ayatollahi, S ; Sharif University of Technology
American Institute of Physics Inc
2021
Abstract
Oil trapping behavior during the pre-flush stage is critically important to evaluate the effectiveness of matrix acidizing for the oil well stimulation. In this study, the visco-capillary behavior of the two-phase flow in the pore-scale is analyzed to investigate the influence of wetting properties for a natural rock sample. A two-dimensional model, based on Cahn-Hilliard phase-field and Navier-Stokes equations, was established and solved using the finite element method. A stability phase diagram for log capillary number (Ca)-log viscosity ratio (M) was constructed and then compared with the reported experimental works. The maximum and minimum ranges of capillary number and viscosity ratio...
Numerical study to evaluate the important parameters affecting the hydrodynamic performance of manta ray's in flapping motion
, Article Applied Ocean Research ; Volume 109 , 2021 ; 01411187 (ISSN) ; Abbaspour, M ; Darbandi, M ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Manta ray swimming or bio-inspiration propulsion system, as a special type of marine propulsion system, is used for submersible vehicles that require high-speed maneuverability and stability, such as glider and AUV. In a manta ray swimming, the thrust force is generated by a couple of undulation and oscillation of wing, so that the direction of undulation wave and oscillation is upright and perpendicular to the direction of thrust force, respectively. It is possible to combine these two movement modes (flapping motion) on the three-dimensional model without considering the effects of wing twisting and flexibility to simplify and better understand the physical behaviors or special study of...
On the stability of rotating pipes conveying fluid in annular liquid medium
, Article Journal of Sound and Vibration ; Volume 494 , 2021 ; 0022460X (ISSN) ; Dehghani Firouz-abadi, R ; Rahmanian, M ; Sharif University of Technology
Academic Press
2021
Abstract
This study provides a stability analysis of flexible rotating pipes taking into account the simultaneous effects of internal and external fluid loading. Using the Euler-Bernoulli beam assumptions, governing equations for flexural vibrations of rotating pipes are obtained. The internal flow characteristics and the double gyroscopic effect are taken into account when deriving the structural equations coupled with the internal flow. External fluid loading is determined by a special linearization of the Navier-Stokes equations. Considering the circular wall of the pipe as an impermeable boundary to the flow, fluid-induced forcing functions are obtained and then applied to the structural...
Pore-doublet computational fluid dynamic simulation of the effects of dynamic contact angle and interfacial tension alterations on the displacement mechanisms of oil by low salinity water
, Article International Journal of Multiphase Flow ; Volume 143 , 2021 ; 03019322 (ISSN) ; Fatemi, M ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Using our recently developed model, for the first time in the literature, the effect of fluid/fluid and rock/fluid interactions on the performance of Low Salinity Waterflooding (LSWF, as an Enhanced Oil Recovery process) at pore-doublet scale is investigated. The model is incorporated into OpenFOAM and both the Navier-Stokes equation for oil/water two-phase flow and the advection-diffusion equation for ion transport (at both fluid/fluid and rock/fluid interface) are solved via direct numerical simulation (DNS). The model is validated against imbibition and drainage pore-doublet experiments reported in the literature, and then applied to investigate the sole effect of wettability alteration...
Mechanistic study of the effects of dynamic fluid/fluid and fluid/rock interactions during immiscible displacement of oil in porous media by low salinity water: Direct numerical simulation
, Article Journal of Molecular Liquids ; Volume 322 , 2021 ; 01677322 (ISSN) ; Fatemi, M ; Sharif University of Technology
Elsevier B.V
2021
Abstract
Low salinity waterflooding (LSWF) is a process in which by lowering the ionic strength and/or manipulation of the composition of the injection water, the long term equilibrium in oil/brine/rock system is disturbed to reach a new state of equilibrium through which the oil production will be enhanced due to fluid/fluid and/or rock/fluid interactions. In spite of recent advances in the simulation of the LSWF at core scale and beyond, there are very few works that have modelled and simulated this process at the pore scale specially using direct numerical simulation (DNS). As a result the effects of wettability alteration and/or Interfacial Tension (IFT) change on the distribution of the phases...
On the stability of rotating pipes conveying fluid in annular liquid medium
, Article Journal of Sound and Vibration ; Volume 494 , 2021 ; 0022460X (ISSN) ; Dehghani Firouz-abadi, R ; Rahmanian, M ; Sharif University of Technology
Academic Press
2021
Abstract
This study provides a stability analysis of flexible rotating pipes taking into account the simultaneous effects of internal and external fluid loading. Using the Euler-Bernoulli beam assumptions, governing equations for flexural vibrations of rotating pipes are obtained. The internal flow characteristics and the double gyroscopic effect are taken into account when deriving the structural equations coupled with the internal flow. External fluid loading is determined by a special linearization of the Navier-Stokes equations. Considering the circular wall of the pipe as an impermeable boundary to the flow, fluid-induced forcing functions are obtained and then applied to the structural...
Pore-doublet computational fluid dynamic simulation of the effects of dynamic contact angle and interfacial tension alterations on the displacement mechanisms of oil by low salinity water
, Article International Journal of Multiphase Flow ; Volume 143 , 2021 ; 03019322 (ISSN) ; Fatemi, M ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Using our recently developed model, for the first time in the literature, the effect of fluid/fluid and rock/fluid interactions on the performance of Low Salinity Waterflooding (LSWF, as an Enhanced Oil Recovery process) at pore-doublet scale is investigated. The model is incorporated into OpenFOAM and both the Navier-Stokes equation for oil/water two-phase flow and the advection-diffusion equation for ion transport (at both fluid/fluid and rock/fluid interface) are solved via direct numerical simulation (DNS). The model is validated against imbibition and drainage pore-doublet experiments reported in the literature, and then applied to investigate the sole effect of wettability alteration...
Mechanistic study of the effects of dynamic fluid/fluid and fluid/rock interactions during immiscible displacement of oil in porous media by low salinity water: direct numerical simulation
, Article Journal of Molecular Liquids ; Volume 322 , 2021 ; 01677322 (ISSN) ; Fatemi, M ; Sharif University of Technology
Elsevier B.V
2021
Abstract
Low salinity waterflooding (LSWF) is a process in which by lowering the ionic strength and/or manipulation of the composition of the injection water, the long term equilibrium in oil/brine/rock system is disturbed to reach a new state of equilibrium through which the oil production will be enhanced due to fluid/fluid and/or rock/fluid interactions. In spite of recent advances in the simulation of the LSWF at core scale and beyond, there are very few works that have modelled and simulated this process at the pore scale specially using direct numerical simulation (DNS). As a result the effects of wettability alteration and/or Interfacial Tension (IFT) change on the distribution of the phases...
Pore-scale simulation of calcite matrix acidizing with hydrochloric acid
, Article SPE Journal ; Volume 26, Issue 2 , 2021 , Pages 653-666 ; 1086055X (ISSN) ; Sharif University of Technology
Society of Petroleum Engineers (SPE)
2021
Abstract
A continuum hydrodynamic model with immersed solid/fluid interface is developed for simulating calcite dissolution by hydrochloric acid (HCl) at the pore scale, and is most accurate for a mass-transfer-controlled dissolution regime under laminar flow conditions. The model uses averaged Navier-Stokes equations to model momentum transfer in porous media and adopts a theoretically developed mass-transfer formulation with assumptions. The model includes no fitting parameter and is validated using experimental results. The findings of previous research and existing models are briefly discussed and their shortcomings and advantages are elucidated. The present model is used in some pore-scale...
Investigation of the impacts of the refill valve diameter on prestrike occurrence in gas circuit breakers
, Article Physics of Fluids ; Volume 33, Issue 8 , August , 2021 ; 10706631 (ISSN) ; Kazempour, A ; Gholami, A ; Sharif University of Technology
American Institute of Physics Inc
2021
Abstract
In puffer type Sulfur Hexafluoride (SF6) Circuit Breakers (CBs), the refill valve is the main inlet duct for the SF6 gas to enter the puffer volume. When the CB is closing and moving contacts and the nozzle are moving toward fixed contacts, the SF6 gas enters the puffer volume via the refill valve. Since changing the refill valve diameter can alter the direction of the SF6 gas motion in the closing operation of CBs, understanding its effects on CBs' function and performance may help to improve the CB design. This paper has focused on the effects of refill valve diameter on prestrike occurrence in the closing operation of puffer type SF6 CBs. In order to accurately study these effects, some...
Dynamics and stability analysis of rotating cylindrical shells in annular fluid medium
, Article International Journal of Structural Stability and Dynamics ; Volume 20, Issue 8 , 2020 ; Firouz Abadi, R. D ; Rahmanian, M ; Sharif University of Technology
World Scientific
2020
Abstract
Stability and dynamics of rotating coaxial cylindrical shells conveying incompressible and inviscid fluid are investigated. The interior shell is assumed to be flexible while the exterior cylinder is rigid. Using Sander's-Koiter theory assumptions and following Hamilton's principle, governing equations of motion are determined in their integral form. Employing the extended Galerkin method of solution, the integral equations of motion are projected to their equivalent system of algebraic equations. Fluid equations are fundamentally based on the linearized inviscid Navier-Stokes equations. Impermeability condition on the fluid and structure interface as well as the zero radial velocity...