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Earth is the only known planet with plate tectonics, which involves a mobile upper thermal boundary layer. Other terrestrial planets show a one-plate immobile lithosphere, or stagnant lid, that insulates and isolates their interior. Here, we first review the different types of lids that can develop on rocky and icy bodies. As they formed by accretion, involving high-energy impacts, terrestrial planets likely started hot and molten. We examine the process of lid initiation from a magma ocean stage and develop the equations for lid growth. We survey how lateral perturbations in lid and crust thickness can be amplified during their growth and finally discuss the possible processes at the origin of lid rupture and plate generation.
Our understanding of respiratory flow phenomena has been consolidated over decades with the exploration of in vitro and in silico canonical models that underscore the multiscale fluid mechanics spanning the vast airway complex. In recent years, there has been growing recognition of the significant intersubject variability characterizing the human lung morphometry that modulates underlying canonical flows across subjects. Despite outstanding challenges in modeling and validation approaches, exemplified foremost in capturing chronic respiratory diseases, the field is swiftly moving toward hybrid in silico whole-lung simulations that combine various model classes to resolve airflow and aerosol transport spanning the entire respiratory tract over cumulative breathing cycles. In the years to come, the prospect of accessible, community-curated datasets, in conjunction with the use of machine learning tools, could pave the way for in silico population-based studies to uncover unrecognized trends at the population level and deliver new respiratory diagnostic and pulmonary drug delivery endpoints.
This review provides a comprehensive analysis of the literature on vortex-induced vibration (VIV) of flexible circular cylinders in cross-flow. It delves into the details of the underlying physics governing the VIV dynamics of cylinders characterized by low mass damping and high aspect ratio, subject to both uniform and shear flows. It compiles decades of experimental investigations, modeling efforts, and numerical simulations and describes the fundamental findings in the field. Key focal points include but are not limited to amplitude–frequency response behavior, the relationship between the distributed loading acting on the cylinder and the trajectories and the near wake structures around the cylinder, the existence of traveling waves, the identification of power-in/power-out regions, and the modal overlapping and mode competition phenomena.
By imploding fuel of hydrogen isotopes, inertial confinement fusion (ICF) aims to create conditions that mimic those in the Sun's core. This is fluid dynamics in an extreme regime, with the ultimate goal of making nuclear fusion a viable clean energy source. The fuel must be reliably and symmetrically compressed to temperatures exceeding 100 million degrees Celsius. After the best part of a century of research, the foremost fusion milestone was reached in 2021, when ICF became the first technology to achieve an igniting fusion fuel (thermonuclear instability), and then in 2022 scientific energy breakeven was attained. A key trade-off of the ICF platform is that greater fuel compression leads to higher burn efficiency, but at the expense of amplified Rayleigh–Taylor and Richtmyer–Meshkov instabilities and kinetic-energy-wasting asymmetries. In extreme cases, these three-dimensional instabilities can completely break up the implosion. Even in the highest-yielding 2022 scientific breakeven experiment, high-atomic-number (high-Z) contaminants were unintentionally injected into the fuel. Here we review the pivotal role that fluid dynamics plays in the construction of a stable implosion and the decades of improved understanding and isolated experiments that have contributed to fusion ignition.
Raye Jean Montague (1935–2018) was a computer programmer and self-taught engineer who was at the forefront of modernizing naval architecture and naval engineering through the use of computer-aided design. In this biographical review, she is referred to as Montague, the surname she had for much of her professional life. Since she was a working engineer rather than a scholar, she did not create a publication record by which her achievements can be easily tracked, but her name appears in committee memberships, conference and working group proceedings, and other such interstices of computer-aided ship design. This key contributor to computer-aided design and manufacturing and to naval engineering is well worth getting to know.
Thermoacoustic instability is a flow instability that arises due to a two-way coupling between acoustic waves and unsteady heat release rate. It can cause damaging, large-amplitude oscillations in the combustors of gas turbines, aeroengines, rocket engines, etc., and the transition to decarbonized fuels is likely to introduce new thermoacoustic instability problems. With a focus on practical thermoacoustic instability problems, especially in gas turbine combustors, this review presents the common types of combustor and burner geometry used. It discusses the relevant flow physics underpinning their acoustic and unsteady flame behaviors, including how these differ across combustor and burner types. Computational tools for predicting thermoacoustic instability can be categorized into direct computational approaches, in which a single flow simulation resolves all of the most important length scales and timescales, and coupled/hybrid approaches, which couple separate computational treatments for the acoustic waves and flame, exploiting the large disparity in length scales associated with these. Examples of successful computational prediction of thermoacoustic instability in realistic combustors are given, along with outlooks for future research in this area.
The problem of the geodynamo is simple to formulate (Why does the Earth possess a magnetic field?), yet it proves surprisingly hard to address. As with most geophysical flows, the fluid flow of molten iron in the Earth's core is strongly influenced by the Coriolis effect. Because the liquid is electrically conducting, it is also strongly influenced by the Lorentz force. The balance is unusual in that, whereas each of these effects considered separately tends to impede the flow, the magnetic field in the Earth's core relaxes the effect of the rapid rotation and allows the development of a large-scale flow in the core that in turn regenerates the field. This review covers some recent developments regarding the interplay between rotation and magnetic fields and how it affects the flow in the Earth's core.
Many flows that are expected to be symmetric are actually observed to be asymmetric. The appearance of asymmetry in the face of no particular cause is a widespread although underappreciated occurrence. This rather puzzling and sometimes frustrating phenomenon can occur in wide-angle diffusers, over the forebody of axisymmetric bodies at high angles of attack, in the wake downstream of streamlined as well as bluff bodies, and in the flow over three-dimensional bumps and ramps. We review some notable examples and highlight the extreme sensitivity of many such flows to small disturbances in the body geometry or the incoming flow. Some flows appear to be permanently asymmetric, while others are bistable on timescales that are orders of magnitude longer than any convective timescale. Convective or global instabilities can occur, bistability is common, and mode interactions become important when multiple similar but distinct timescales and length scales are present. Our understanding of these phenomena is still very limited, and further research is urgently required; asymmetries in otherwise symmetric flows can have serious real-world consequences on vehicle control and performance.
The environmental setting of the Dead Sea combines several aspects whose interplay creates flow phenomena and transport processes that cannot be observed anywhere else on Earth. As a terminal lake with a rapidly declining surface level, the Dead Sea has a salinity that is close to saturation, so that the buoyancy-driven flows common in lakes are coupled to precipitation and dissolution, and large amounts of salt are being deposited year-round. The Dead Sea is the only hypersaline lake deep enough to form a thermohaline stratification during the summer, which gives rise to descending supersaturated dissolved-salt fingers that precipitate halite particles. In contrast, during the winter the entire supersaturated, well-mixed water column produces halite. The rapid lake level decline of O(1 m/year) exposes vast areas of newly formed beach every year, which exhibit deep incisions from streams. Taken together, these phenomena provide insight into the enigmatic salt giants observed in the Earth's geological record and offer lessons regarding the stability, erosion, and protection of arid coastlines under sea level change.
Publication date: 15 August 2025
Source: Computers & Fluids, Volume 298
Author(s): Ilham Asmouh, Abdelouahed Ouardghi
Publication date: 15 August 2025
Source: Computers & Fluids, Volume 298
Author(s): Hugo Dornier, Olivier P. Le Maître, Pietro M. Congedo, Itham Salah el Din, Julien Marty, Sébastien Bourasseau
Publication date: 15 August 2025
Source: Computers & Fluids, Volume 298
Author(s): Qiuyu Sheng, Haijian Yang, Huangxin Chen, Tianpei Cheng, Shuyu Sun
Publication date: 15 August 2025
Source: Computers & Fluids, Volume 298
Author(s): E. Tarik Balci, Paul Anderson, Elaine S. Oran
Publication date: 15 August 2025
Source: Computers & Fluids, Volume 298
Author(s): Chunheng Zhao, Saumil Patel, Taehun Lee
Publication date: 30 August 2025
Source: Computers & Fluids, Volume 299
Author(s): Yannick Schubert, Ennes Sarradj, Mathias Lemke
Publication date: 15 August 2025
Source: Computers & Fluids, Volume 298
Author(s): Roxana Bujack, Mikhail Shashkov
Publication date: 15 August 2025
Source: Computers & Fluids, Volume 298
Author(s): R. Abaidi, N.A. Adams
Publication date: 15 August 2025
Source: Computers & Fluids, Volume 298
Author(s): Samuel Altland, Vishal Wadhai, Shyam Nair, Xiang Yang, Robert Kunz, Stephen McClain
Publication date: 15 August 2025
Source: Computers & Fluids, Volume 298
Author(s): Howon Lee, Aanchal Save, Pranay Seshadri, Juergen Rauleder
Compared to experimental data of thermophysical properties of NFs, semi-empirical models cannot estimate FOM correctly. For all working fluids, applying a converging channel instead of the canonical case was inefficient. Diverging channel was always favored compared to the canonical case. For less effective NFs, both lowering the reference velocity and a diverging channel are preferred.
Researchers have proposed multifarious passive methods for heat transfer augmentation over geometries with separation and reattachment. In this study, the turbulent forced convection flow of water-based CNT-TiO2 hybrid nanofluid, ND-Ni hybrid nanofluid, and mono Ni nanofluid (with temperature-dependent properties) in a double forward-facing step channel with a converging/diverging bottom adiabatic wall is evaluated. The single-phase shear stress transport k-ω model is applied to solve the governing equations. Results indicate that the highest thermo-hydraulic performance (the value of figure-of-merit is equal to 1.1) can be achieved using TiO2-CNT/water HyNf with ϕ = 0.002. Generally, as the velocity of the incoming stream is reduced, the thermal efficacy of HyNf improves. When the water-based NFs are not an effective heat transfer fluid (inducing a performance evaluation criterion lower than unity), the diverging channel (weakening of the contact between surfaces with constant heat flux and working fluid) can be employed instead of the DFFS channel while the Reynolds number of the incoming flow reduces as well. It is found that the thermal efficacy of water-based NFs in complex separated flows depends strongly not only on the deflection angle of the bottom adiabatic wall but also on the velocity of the incoming flow.
We propose in this article a new three-directional orthogonality preserving method (TDOP) for hyperbolic grid generation. Compared with the traditional method that sacrifices the orthogonal constraint on the advancing front layer, TDOP derives new governing equations for hyperbolic grid generation that can take all orthogonal constraints into consideration. Results of application cases demonstrate that TDOP can generate computational grids with higher quality than the traditional method.
The hyperbolic grid generation method is widely used for generating computational grids. Because of conflicts arising from various grid constraints, the traditional hyperbolic grid generation method faces challenges in guaranteeing the fulfillment of all orthogonal constraints among three directions during the grid generation. A new three-directional orthogonality preserving method (TDOP) is introduced in the present work to enhance the orthogonality of the computational grid during the grid generation process. Unlike the traditional grid generation method, TDOP takes all three orthogonal constraints into consideration, establishes a function to quantify the overall grid orthogonality, and subsequently derives new governing equations for grid generation by solving a constrained optimization problem. Compared with the traditional method, TDOP exhibits enhanced control over the orthogonality among three directions, thereby enabling the generation of a computational grid with better orthogonality. Three application cases are employed to demonstrate the effectiveness and superiority of TDOP in hyperbolic grid generation. Results indicate that, compared with the traditional method, TDOP can effectively prevent the emergence of highly skewed grids and enables enhanced optimization of orthogonality in the advancing front layer. Consequently, TDOP can generate a computational grid with better orthogonality and higher quality than the traditional method.
In this article, A Higher order numerical algorithm based on LDG and SDC method for the rotating Navier–Stokes equations are presented. Moreover, the stability of the second-order fully discrete method is proved. Finally, the theoretical results and effectiveness are verified through numerical examples.
In this article, the spatial local discontinuous Galerkin (LDG) method and the temporal spectral deferred correction (SDC) method are combined to construct the higher-order approximating method for the unsteady rotating Navier–Stokes equations on the triangular mesh. First, the artificially compressible method is used to circumvent the incompressibility constraint, and the rotating Navier–Stokes equations are transformed into the artificially compressible rotating Navier–Stokes equations. Then, based on equal LDG interpolation and repeated temporal SDC, the higher-order fully discrete method is presented. Theoretically, the stability analysis of the second-order fully discrete method is provided, and it is shown that the time step τ$$ \tau $$ is stable within the upper bound constraints. Numerical examples are presented to demonstrate the effectiveness of the proposed method.
Compared with the HLLD solver, the slow waves are allowed to persist inside the Riemann fan, so that the two Alfven waves are replaced by the two compound waves. The numerical tests showed that the extended HLLD solver has better performance for the capture of slow waves than the HLLD solver, and exhibits overall better accuracy in some situations where the slow waves exist.
By revisiting the derivation of multi-state HLL approximate Riemann solver for the ideal magneto-hydrodynamics, an extended HLLD Riemann solver is constructed based on the assumption that the normal velocity is constant over the Riemann fan, which is bounded by two fast waves, and separated by two compound waves and a middle contact wave. Compared with the HLLD solver, the slow waves are allowed to persist inside the Riemann fan, so that the two Alfvén waves are replaced by the two compound waves that are the merging product of the Alfvén and slow waves. Conseq uently, the corresponding wave speeds are chosen to be an interpolation between the Alfvén and slow waves for simplicity. The numerical tests showed that the extended HLLD solver (called HLLD-P) has better performance for the capture of slow waves than the HLLD solver, and exhibits overall better accuracy in some situations where the slow waves exist. However, the new solver does not capture the Alfvén wave as well as the HLLD solver once the estimated speeds of compound waves deviate from the Alfvén wave speeds. Overall, the HLLD-P solver is fully compatible with the HLLD solver as long as the compound waves degenerate to the Alfvén waves inside the Riemann fan. It is indicated that the HLLD-P solver can be used for the various applications of MHD simulation, especially for those cases where the slow waves are expected to be generated.
A cavitation implementation algorithm is developed using a pressure-based method for incompressible flows with three-phase interactions, which involve high Reynolds number multi-phase turbulent flows interacting with moving bodies of complex geometries.
In the present study, a cavitation implementation algorithm is developed using a pressure-based method for incompressible flows with three-phase interactions. Central to this implementation algorithm is the treatment of the velocity jump due to the phase change, which is included in both the cavitation transport and pressure equations. The velocity jump, as a function of the phase change rate, is added as a source term to the pressure Poisson equation. A non-conservative form of the vapor transport equation is derived, and the velocity divergence is replaced by a term related to the mass phase change rate. An algorithm for the three-phase (air, water, and vapor) interactions is also developed. The VOF method is modified and used to identify the ‘dry’ (air) phase and the ‘wet’ (water/vapor mixture) phase, since the cavitation can only occur inside the water phase. The liquid volume fraction is used to distinguish water and vapor phases. The numerical results of the 2D NACA66MOD and 3D Delft Twist 11 hydrofoils show good agreement with the experimental measurement. The forced unsteady cavitation flows are investigated using a pitching foil with the results compared with the experimental observations. Air–water interface effect on the cavitation is investigated using the NACA66MOD hydrofoil. The code is applied to simulate a surface piercing super cavitating hydrofoil with both ventilation and cavitation involved.
An extended height function method for 3D VOF simulations applicable to the wetting phenomena on super-hydrophilic and super-hydrophobic surfaces is proposed. By implementing specific treatments of contact line identification and height function construction, reflecting the contact angle boundary condition, the proposed method ensures the first- or second-order convergence of the curvature at the contact line for a wide range of contact angles. Additionally, droplet spreading driven by surface tension on solid walls can be reproduced.
An extended height-function (HF) method that can be consistently utilized for 3D volume of fluid (VOF) simulations of wetting phenomena on super-hydrophilic and super-hydrophobic surfaces, is proposed. First, the standard HF method is briefly explained. Then, 2D and 3D HF methods that reflect the contact angles reported so far are described, with their limitations discussed. Finally, specific treatments of contact line identification and HF construction reflecting the contact angle boundary condition, required to overcome such limitations, are presented in detail. Numerical tests for a sessile droplet reveal that the contact line identification and HF construction are conducted appropriately with respect to the imposed contact angles ranging from 15∘$$ 1{5}^{\circ } $$ to 165∘$$ 16{5}^{\circ } $$ in the proposed numerical scheme. Additionally, the present method shows approximately first- or second-order convergence of the curvature at the contact line for a wide range of contact angles. Moreover, simulations of droplet spreading driven by surface tension reveal that the proposed method can reasonably reproduce the behavior of a droplet reaching an equilibrium state defined by an imposed contact angle.
The approximational solution is decomposed into large and small eddy components. The high-precision solver is used to obtain the large eddy components and the low-precision solver is used to obtain the small eddy components since that the small eddy components carry a little part of the total energy. Numerical tests present the efficiency of the mixed-precision method.
In this article, a local and parallel mixed-precision finite element method is applied for solving the time-dependent incompressible flows. We decompose the solution into the large eddy components and small eddy components based on two-grid method. The analysis shows that the small eddy components carry little part of the total energy compared with the large eddy components. In view of this character, we first obtain the large eddy components by solving the standard nonlinear equation using the high-precision solvers globally in the coarse mesh space, then get the small eddy components by solving a series of local linearized residual equation using the low-precision solvers locally and parallel based on the partition of unity. The performance advantages of the mixed-precision methods are tested with respect to speedups over a high-precision implementation in time and less storage requirements in space.
This paper presents different methods for generating clouds of points around objects for use with meshless methods in computational fluid dynamics. This image shows the cloud generated around the original ROBIN body.
Meshing is a bottleneck of CFD workflows, especially when complex geometries are considered. Mesh-free methods could be a promising solution, but the lack of high-quality point cloud generation methods for boundary layers has hindered their popularity and applications. This work presents a novel point cloud generation framework for near- and off-body regions. The novelty of the method is the introduction of the Signed Distance Function (SDF) to guide advancing point layers in the near-body region. Insertion/removal mechanisms of points, collocation search approach, and point cloud quality metrics were also proposed. These ensure high-quality boundary layer resolution in the near-body region, regardless of the complexity and topology of the geometry. For the off-body region, Cartesian points are employed for smooth and adaptive point distributions. Compared to conventional advancing front point generation, the proposed method ensures surface-norm point distributions with consistent layer structures, which are critical for boundary layer resolution. Compared to the strand mesh generation, the current method presents much greater flexibility with few restrictions on inter-layer connections. The proposed approach is tested for various 2D and 3D benchmark geometries, along with mesh-free modeling results using the generated point clouds. The results demonstrate an important step towards a fully automated, adaptive, and mesh-free CFD workflow for complex engineering applications.
In the process of injection molding, shrinkage and warpage can lead to variations in the size and shape of produced parts compared to the cavity shape. Our research evaluated different algorithms for warpage compensation in injection molding. Our main finding was that the reverse geometry method consistently outperformed other tested algorithms on all geometries and is the most straightforward to implement.
In injection molding processes, shrinkage and warpage cause deviations in the size and shape of produced parts compared to the cavity shape. While shrinkage is due to the change of material density during solidification, warpage is caused by uneven cooling and internal stresses within the part. One approach to mitigate these effects is by adjusting the cavity shape to anticipate the deformation. While finding the optimal cavity shape is often experience-based in practice, numerical design optimization can greatly assist in this process. In this study, we evaluate various numerical algorithms from existing literature to identify the optimal cavity shape. Each method is briefly outlined regarding how it adapts the geometry, and we discuss their respective strengths and weaknesses for different scenarios. We conduct comparisons using 3D geometries of varying complexity. Our findings demonstrate that, for geometric warpage compensation, the node-based reverse geometry method yields the least warpage and is computationally cost-effective. Furthermore, it is straightforward to implement and consistently performs well across different geometries.
Publication date: 15 September 2025
Source: Journal of Computational Physics, Volume 537
Author(s): Wai Ming Chau, Shingyu Leung
Publication date: 15 September 2025
Source: Journal of Computational Physics, Volume 537
Author(s): Vishnu Prakash K, Ganesh Natarajan
Publication date: 15 September 2025
Source: Journal of Computational Physics, Volume 537
Author(s): Hao Yang, Kaikai Feng, Ziqi Cui, Jun Zhang
Publication date: 15 September 2025
Source: Journal of Computational Physics, Volume 537
Author(s): Zhenyu Hu, Yu Yuan, Dapeng Xiong, Chenglong Wang, Mingbo Sun, Yongchao Sun
Publication date: 15 September 2025
Source: Journal of Computational Physics, Volume 537
Author(s): Yue Wu, Chi-Wang Shu
Publication date: 15 September 2025
Source: Journal of Computational Physics, Volume 537
Author(s): Vasiliy A. Es’kin, Alexey O. Malkhanov, Mikhail E. Smorkalov
Publication date: 15 September 2025
Source: Journal of Computational Physics, Volume 537
Author(s): Golo A. Wimmer, Ben S. Southworth, Qi Tang
Publication date: 15 September 2025
Source: Journal of Computational Physics, Volume 537
Author(s): Ruifeng Yuan, Lei Wu
Publication date: 15 September 2025
Source: Journal of Computational Physics, Volume 537
Author(s): Jingrun Chen, Zheng Ma, Keke Wu
Publication date: 15 September 2025
Source: Journal of Computational Physics, Volume 537
Author(s): Ilker Topcuoglu, Xiang Yang, Robert Kunz
