Article
Mechanics
Jiacheng Chen, Wendong Liang, Lei Han, Yanfei He, Tairan Chen
Summary: The study aims to propose numerical methods for compressible cryogenic cavitating flows and investigate cavitation behaviors and vortex structures. A numerical modeling framework, including large eddy simulations, vapor-liquid equations of state, and a modified mass transport model, is presented. The modified model is validated by simulating liquid nitrogen cavitating flows under inertial and thermal modes, and the influence of thermodynamic effects on compressibility is investigated. The results show that the modified model agrees better with experimental data.
Article
Mechanics
Aditya Madabhushi, Krishnan Mahesh
Summary: We propose a compressible multi-scale model that captures the dynamics of both large vapour cavities and micro-bubbles and takes into account the compressibility of the medium. The model tracks the homogeneous mixture of liquid and resolved vapour in an Eulerian sense and tracks the unresolved vapour in a Lagrangian sense using a novel equation. The model has been validated and shown to accurately capture the collapse of single and multiple bubbles, as well as the interaction between bubbles in a cluster.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Physics, Fluids & Plasmas
Changchang Wang, Guoyu Wang, Mindi Zhang, Biao Huang, Yi-Qing Ni
Summary: This study investigates the wall-pressure fluctuations in high Reynolds number cavitating flows and provides insights into their characteristics and behaviors. The results show that the amplitude of wall-pressure fluctuations is independent of the cavitation number and reaches its maximum near the cavity closure. The probability density function of wall-pressure fluctuations exhibits non-Gaussian and asymmetric shapes. Spectral analysis reveals different scaling behaviors in different frequency ranges. Additionally, the study highlights the significant influence of Reynolds number on the non-Gaussian and asymmetric behaviors of wall-pressure fluctuations.
PHYSICAL REVIEW FLUIDS
(2023)
Article
Optics
V. Sridhar, K. Hiraki, S. L. Gai, H. Kleine
Summary: This paper discusses the characteristics, advantages, and limitations of a digital version of the traditional streak imaging technique combined with various flow visualization methods. It also presents several applications in fluid mechanics. Streak images are useful for tracking and quantifying the development and propagation of different flow features over time and can graphically reveal the onset of certain flow phenomena. The digital technique also has the ability to filter and display less prominent elements of the flow.
OPTICS AND LASERS IN ENGINEERING
(2023)
Article
Engineering, Aerospace
Kung-Ming Chung, Yi-Xuan Huang
Summary: This study used pressure-sensitive paint (PSP) to determine the surface pressure distributions for a compressible swept convex-corner flow. It found greater spanwise pressure gradient and curved shocks in the case of shock-induced boundary layer separation. The PSP data agreed with experimental data for subsonic expansion flow but showed significant discrepancy for transonic expansion flow, requiring temperature correction.
Article
Thermodynamics
Wendong Liang, Tairan Chen, Guoyu Wang, Biao Huang
Summary: The study aims to investigate the transient dynamics of liquid nitrogen cavitation flows under various free-stream conditions. Improved temporal and spatial resolution of cavity images reveals detailed cavity structures and unsteady behaviors. Analysis using Proper Orthogonal Decomposition (POD) method based on clear experimental images shows changes in spatial structures, shedding behaviors of detached cloud cavities, and condensation rates of discrete cavity bubbles under different temperature conditions.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2021)
Article
Mechanics
Kunpeng Long, Olivier Coutier-Delgosha, Annie-Claude Bayeul-Laine
Summary: The paper focuses on the three-dimensional effects in a cavitating flow in a venturi-type profile. Experimental measurements based on 2D3C stereoscopic particle image velocimetry are conducted to obtain the three components of the velocity field in multiple vertical planes. The study reveals the presence of significant flow velocities in the third direction, attributed to differences in boundary conditions and intrinsic three-dimensional mechanisms inside the cavitation area.
Article
Mathematics, Interdisciplinary Applications
David Codoni, Georgios Moutsanidis, Ming-Chen Hsu, Yuri Bazilevs, Craig Johansen, Artem Korobenko
Summary: A stable finite element framework for high-speed compressible flows is proposed, utilizing the Streamline-Upwind/Petrov-Galerkin formulation and discontinuity-capturing techniques. The accuracy of full- and reduced-energy formulations is assessed, with a specific focus on a DC formulation suited for hypersonic flows. Verification and validation cases across various flow regimes demonstrate the excellent performance of the framework for advanced applications.
COMPUTATIONAL MECHANICS
(2021)
Article
Mechanics
Christian Lang, Oliver Boolakee, Steffen J. Schmidt, Nikolaus A. Adams
Summary: A fully compressible, density-based finite volume solver is presented for the simulation of 3D cavitating flows in viscoelastic Maxwell-/Oldroyd-like fluids. Different viscoelastic constitutive equations, including the Oldroyd-B model and simplified Phan-Thien Tanner models, are implemented in conservative formulation. The study shows the distinct influence of relaxation time variations on the dynamics of cavitating flows in different viscoelastic models.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2022)
Article
Computer Science, Interdisciplinary Applications
Francois Bouchut, Enrique D. Fernandez-Nieto, El Hadji Kone, Anne Mangeney, Gladys Narbona-Reina
Summary: This study investigates the dilatancy effects in dry granular flows, revealing that initial volume fraction affects the height of deposits but has little impact on the front position and deposit shape. The model predicts increasing dilation of the mass with increasing slopes, indicating the key role of dilatancy in describing granular flows.
JOURNAL OF COMPUTATIONAL PHYSICS
(2021)
Article
Acoustics
L. Perrin, D. Colombet, F. Ayela
Summary: Luminescence and chemiluminescence were experimentally investigated in hydrodynamic cavitating flows using dedicated microdevices for photon counting. Luminescence was studied with deionized water as the working fluid, while chemiluminescence was observed in cavitating alkaline luminol solutions correlated to hydroxyl radicals formation. Degassed solutions enhanced the luminescence and hydroxyl radical yield, suggesting new perspectives for using hydrodynamic cavitation as an advanced oxidation process.
ULTRASONICS SONOCHEMISTRY
(2021)
Article
Mechanics
Amirhossein Mohammadkhani, Mansour Alizadeh
Summary: This study introduces a new numerical approach based on IDDES turbulence modeling for predicting cavitation flows, successfully validating the accuracy of predicting cavitation erosion locations and features in hydrodynamic cavitation flows.
JOURNAL OF HYDRODYNAMICS
(2021)
Article
Mechanics
Taihei Onishi, Yanbo Peng, Hong Ji, Guoyi Peng
Summary: This paper presents an improved cavitation model for high-speed submerged water jets, considering phase change effects and fluid compressibility. The model is embedded in an unsteady Reynolds-averaged Navier-Stokes solver, and the turbulent cavitating flow caused by an impulsively started submerged water jet is studied. The results show good agreement with experimental results, capturing the periodic shedding of cavitation clouds and providing insights into the cavitation process.
Article
Thermodynamics
Changchang Wang, Guoyu Wang, Mindi Zhang, Biao Huang
Summary: This study investigates the wall pressure fluctuations in compressible turbulent cavitating flows, focusing on their non-Gaussian behaviors and physical mechanisms. The results show that the fluctuations exhibit positive skewness, which is independent of the cavity regime. However, there are differences in the fluctuating pressure signals under different cavity regimes. The Hilbert-Huang transform is used to analyze the fluctuations in cloud cavitation and a physical model based on cavitation bubble dynamics is proposed.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2022)
Article
Mathematics, Applied
Ramesh Kolluru, N. V. Raghavendra, S. V. Raghurama Rao, G. N. Sekhar
Summary: The study aims to develop simple algorithms to address the numerical simulation issues related to the hyperbolic nonlinear convection terms in compressible fluid flows. By utilizing central schemes with smart diffusion mechanisms and satisfying Rankine-Hugoniot conditions and generalized Riemann invariants, two algorithms have been successfully developed to avoid numerical shock instabilities. Both algorithms are robust in avoiding shock instabilities, accurately capture contact discontinuities, do not require wave speed corrections, and are independent of the eigenstructure of the underlying hyperbolic parts of the systems.
APPLIED MATHEMATICS AND COMPUTATION
(2022)
Article
Engineering, Multidisciplinary
H. Y. Cheng, X. R. Bai, X. P. Long, B. Ji, X. X. Peng, M. Farhat
APPLIED MATHEMATICAL MODELLING
(2020)
Article
Engineering, Mechanical
Huaiyu Cheng, Xinping Long, Bin Ji, Xiaoxing Peng, Mohamed Farhat
EXPERIMENTS IN FLUIDS
(2020)
Article
Mechanics
Huaiyu Cheng, Xinping Long, Bin Ji, Xiaoxing Peng, Mohamed Farhat
Summary: This study introduces a new numerical simulation model for tip vortex cavitation that takes into account the influence of non-condensable gas. By considering gas content, a significant improvement in predicting tip vortex cavitation was achieved. The research highlights the crucial role of gas content in cavitation development.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2021)
Article
Engineering, Mechanical
Mohammad Hossein Arabnejad, Urban Svennberg, Rickard E. Bensow
Summary: The paper proposes a numerical method based on energy description to assess the risk of cavitation erosion, with two improvements compared to other methods. Validation with experimental data shows good agreement between predicted high erosion risk areas and experimental erosion patterns. The method can also be used to study the relationship between cavity dynamics and cavitation erosion risk.
Article
Computer Science, Interdisciplinary Applications
Mohamad Sadeq Karimi, Mehrdad Raisee, Mohamed Farhat, Patrick Hendrick, Ahmad Nourbakhsh
Summary: The study investigates the effects of operational and geometrical uncertainties on Tip Leakage Vortex (TLV) characteristics, showing profound impacts on cavitating tip leakage vortex flow, lift, and drag coefficients, and describing the discrepancies between numerical and experimental results. Operational uncertainties mainly influence TLV characteristics like circulation and velocity field, while geometrical randomness affects the vortex core position and viscous core radius, specifically gap distance.
COMPUTERS & FLUIDS
(2021)
Review
Mechanics
Huai-yu Cheng, Bin Ji, Xin-ping Long, Wen-xin Huai, Mohamed Farhat
Summary: The TLV cavitation poses challenges for axial hydraulic turbines and pumps, with non-condensable gas playing a significant role in its development. Suppressing TLV cavitation remains a difficult question to answer.
JOURNAL OF HYDRODYNAMICS
(2021)
Article
Thermodynamics
Mohammad Shahsavari, Mohammad Farshchi, Mohammad Hossein Arabnejad, Bing wang
Summary: This study investigates flame-flow interactions in lean premixed lifted flame stabilized in a low swirl flow using large eddy simulations. The results show that in addition to the swirling motion, combustion heat release plays a significant role in stabilizing the flame by reducing flow velocity.
COMBUSTION SCIENCE AND TECHNOLOGY
(2023)
Article
Engineering, Mechanical
Mohammad Hossein Arabnejad, Urban Svennberg, Rickard E. Bensow
Summary: This paper assesses the risk of cavitation erosion in a commercial water-jet pump using a newly developed numerical erosion assessment method, comparing high erosion risk areas with experimental results. The method is capable of identifying regions of high erosion risk and highlights differences in cavitation erosion risk between two flow conditions. Analysis of numerical results reveals that stronger flow nonuniformities entering the rotor in the most erosive condition are primarily responsible for the variation in erosion risk.
JOURNAL OF FLUIDS ENGINEERING-TRANSACTIONS OF THE ASME
(2022)
Article
Energy & Fuels
Marc Tinguely, Kiyonobu Ohtani, Mohamed Farhat, Takehiko Sato
Summary: In this study, the formation of multiple shock waves generated by the collapse of a laser-induced bubble was investigated using high-speed imaging technology. The results showed that there is a certain sequence in the generation process of these shock waves.
Article
Mechanics
A. B. Sieber, D. B. Preso, M. Farhat
Summary: In this study, the dynamics of a cavitation bubble near beds of sand with different grain sizes were investigated using high-speed imaging. The results show that compared to a rigid boundary, a granular boundary leads to shorter bubble lifetimes and reduced centroid displacements. The behavior of the bubble is almost independent of the sand granularity within a certain range, and the collapsing bubble can form micro-jets and granular jets.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Engineering, Mechanical
Xiao-Dong Liu, Mohamed Farhat, Yao-Jun Li, Zhu-Qing Liu, Wei Yang
Summary: The efficiency of centrifugal pumps decreases significantly below a certain flowrate, primarily due to flow separation near the impeller blades and the formation of recirculation zones. This study combines experiments and numerical simulations to investigate the initiation of flow separation in centrifugal impellers. The results reveal the existence of a cylindrical vortex band near the impeller shroud, which grows stronger and moves towards the impeller hub as the flowrate decreases. This growing and moving vortex is the main cause of flow separation observed near the blade suction side.
JOURNAL OF FLUIDS ENGINEERING-TRANSACTIONS OF THE ASME
(2023)
Article
Mechanics
A. B. Sieber, D. B. Preso, M. Farhat
Summary: Considerable interest has been devoted to the interactions between cavitation bubbles and tissue-mimicking materials in recent years, as they have promising applications in medicine and biomedical sciences. The fluid-structure interaction between cavitation bubbles and elastic surfaces triggers unique collapse dynamics, including bubble splitting and microjetting phenomena that can cause damage. This study investigates the effect of boundary elasticity and bubble-surface distance on the dynamics of cavitation bubbles and the velocity of microjets. High-speed imaging techniques are used to track the bubble dynamics, with a focus on the formation and evolution of microjets. The study provides evidence of the atomization of liquid microjets within the bubble, followed by the establishment of fully liquid microjets. Supersonic velocities of up to 2000 m/s are achieved by the atomized portion of the microjet, while fully developed liquid microjets travel at averaged speeds of up to 1000 m/s. A numerical model based on the boundary integral method shows remarkable agreement with experimental observations.
Proceedings Paper
Energy & Fuels
S. Maeda, T. Sano, M. Iino, M. Farhat, A. Amini
Summary: This study investigates the impact of winglet attached to an elliptical hydrofoil on performance through numerical simulations and experiments. Results show that increasing the bending angle of the winglet helps decrease TVC, and disappears in case of a 90 degree bending towards the pressure side, mainly due to the mutual weakening effects of the vortices under this condition.
30TH IAHR SYMPOSIUM ON HYDRAULIC MACHINERY AND SYSTEMS (IAHR 2020)
(2021)