Hydrodynamic Constraints Research Articles

Decoupling shear stress and pressure effects in the biomechanics of autosomal dominant polycystic kidney disease using a perfused kidney-on-chip.

Kidney tubular cells are submitted to two distinct mechanical forces generated by the urine flow: shear stress and hydrostatic pressure. In addition, the mechanical properties of the surrounding extracellular matrix modulate tubule deformation under constraints. These mechanical factors likely play a role in the pathophysiology of kidney diseases as exemplified by autosomal dominant polycystic kidney disease, in which pressure, flow and matrix stiffness have been proposed to modulate the cystic dilation of tubules with PKD1 mutations. The lack of in vitro systems recapitulating the mechanical environment of kidney tubules impedes our ability to dissect the role of these mechanical factors. Here we describe a perfused kidney-on-chip with tunable extracellular matrix mechanical properties and hydrodynamic constraints, that allows a decoupling of shear stress and flow. We used this system to dissect how these mechanical cues affect Pkd1 -/- tubule dilation. Our results show two distinct mechanisms leading to tubular dilation. For PCT cells (proximal tubule), overproliferation mechanically leads to tubular dilation, regardless of the mechanical context. For mIMCD-3 cells (collecting duct), tube dilation is associated with a squamous cell morphology but not with overproliferation and is highly sensitive to extracellular matrix properties and hydrodynamic constraints. Surprisingly, flow alone suppressed Pkd1 -/- mIMCD-3 tubule dilation observed in static conditions, while the addition of luminal pressure restored it. Our in vitro model emulating nephron geometrical and mechanical organization sheds light on the roles of mechanical constraints in ADPKD and demonstrates the importance of controlling intraluminal pressure in kidney tubule models.

Locomotory and morphological evolution of the earliest Silurian graptolite Demirastrites selected by hydrodynamics

AbstractInterpretation of the locomotion of biostratigraphically important graptolite taxa is rare, and rendered problematic due to a lack of close modern analogues and soft tissues. In this study, based on well‐preserved specimens of the early Silurian low‐helical spiral Demirastrites Eisel, we reconstructed three‐dimensional Demirastrites models and simulated their locomotion using computational fluid dynamics. Hydrodynamic properties (outer‐wall pressure fields and velocity fields) were obtained and used to test the prevailing hypothesis that the Silurian low helical spiral graptolite Demirastrites could rotate in seawater. The Demirastrites models kept rotating at different velocities in the simulation field, which helped to counteract the impact of the water current and achieve stability. During rotation, higher velocity fields could be observed near the thecal apertures, which meant better access to more nutrient particles in the sea water. Our simulation thus confirmed the rotating locomotory pattern of the Silurian low conical graptolite Demirastrites for the purpose of better feeding efficiency and tubarium stability. Moreover, we analysed how the evolution of structural innovations, such as the density and width of thecae and angle of proximal curvature of the tubarium within the recovered geological lineages of Demirastrites, were influenced and selected by hydrodynamics. The results showed that Demirastrites lineages evolved towards increased stability and higher rotation velocity. Our study highlights the importance of hydrodynamic constraints serving as hidden abiotic factors shaping the evolution of planktonic graptolites.

Analytical Review of Numerical Analysis in Hydrodynamic Performance of the Ship: Effect to Hull-Form Modifications

<span lang="EN-GB">This review paper provides an overview of simulation-based hydrodynamic design optimization for ship hull forms. It also includes a numerical analysis aimed at accomplish early-stage simulation-based design in terms of hydrodynamic performance. A hydrodynamic module, a hull surface modeling module, and an optimization module are the primary components of this numerical analysis. The hydrodynamic module includes both simple design approaches and high-fidelity numeric tools; these integrated tools are used to evaluate hydrodynamic performances at different design stages. The hull surface modeling module offers a variety of techniques for ship hull surface representation and modification. It is also used to automatically create hull forms or change existing hull forms based on hydrodynamic performance and design constraints. The optimization module includes several optimization algorithms and surrogate models used to determine optimal designs in terms of hydrodynamic performance. Numerical findings indicate that the current tool is well suited for hull form design optimization at the early design stage because it can produce effective optimal designs within a short time.</span>

Eukaryotic swimming cells are shaped by hydrodynamic constraints

Eukaryotic swimming cells such as spermatozoa, algae or protozoa use flagella or cilia to move in viscous fluids. The motion of their flexible appendages in the surrounding fluid induces propulsive forces that balance viscous drag on the cells and lead to a directed swimming motion. Here, we use our recently built database of cell motility (BOSO-Micro) to investigate the extent to which the shapes of eukaryotic swimming cells may be optimal from a hydrodynamic standpoint. We first examine the morphology of flexible flagella undergoing waving deformation and show that their amplitude-to-wavelength ratio is near that predicted theoretically to optimise the propulsive efficiency of active filaments. Next, we consider ciliates, for which locomotion is induced by the collective beating of short cilia covering their surface. We show that the aspect ratios of ciliates are close to that predicted to minimise the viscous drag of the cell body. Both results strongly suggest a key role played by hydrodynamic constraints, in particular viscous drag, in shaping eukaryotic swimming cells.

Hydrodynamical constraints on the bubble wall velocity

Hydrodynamical constraints on the bubble wall velocity

Probabilistic surrogate-based optimization of ship hull-propulsor design with bi-level infill sampling technique

This work develops a new multi-level hull-propulsor optimization tool, systematically considering the full range of expected operating conditions. Different solvers with variable fidelities are used to evaluate hydrodynamic objective functions and constraints. The bi-fidelity surrogate model is applied to integrate the accuracy advantage of a medium-fidelity solver with the efficiency advantage of a low-fidelity solver. A bi-level technique of infill sampling integrated with a new version of multi-objective evolutionary algorithms is presented to enhance the effectiveness of the surrogate models. A ship velocity- and sea state-based joint probability density function is employed to take into account the real lifetime operational space. The well-known S175 containership, KP505 propeller and a MAN B&W marine engine are utilized as the initial hull-propulsor model. The final results show that the optimization framework is able to achieve some optimum hull-propulsor designs from the lifetime fuel consumption and energy efficiency design index points of view and to reduce the overall lifetime ownership cost significantly.

Case study of mountainous geothermal reservoirs (Kopaonik Mt., southwestern Serbia): Fault-controlled fluid compartmentalization within a late Paleogene-Neogene core-complex

A composite hydrogeothermal survey of the magmatic-metamorphic post-NeoTethyan late Paleogene - Neogene crustal core-complex of the Kopaonik Mt., southwestern Serbian highlands, provides new constraints on the subsurface hydraulic across- and along-fault flow fluid regimes and geothermal anomalies associated with the two shallow reservoirs. The study is involving synergistic approach by combining structural geology, exploratory drilling, temperature logging, hydrochemical and hydrodynamic constraints further illustrating a complex conduit–barrier fault-controlled spatial compartmentalization of the two thermal water reservoir(s). The thermal waters of the Kopaonik Mt. geothermal field are channeled by the major regional faults and associated fracture zones that are crosscutting the volcanics and the adjoining metamorphites. The results show that the subsurface compartmentalization of the active reservoirs, which are supplying the spa town of Jošanička banja, are controlled by a seismically active regional faults (including the fault that is crosscutting the Slanište locality, having N-S trending). Owing to the linear channeling of the fault-controlled reservoirs, in which the main quantitative water circulation takes place, it was possible to identify the thermal fluid flow paths and associated recharge zones (catchments). The Jošanička banja thermal waters reservoir is accommodated at ca. 400–500 m depth, whereas the Slanište aquifer maintains a shallower position. The new surface - subsurface constraints allowed the estimation of the subsurface reservoir elevations, pinpointing the origin of shallow crustal geothermal processes. Of particular importance is better understanding of the subsurface spatial distribution and the ultimate depth of the developing Kopaonik Mt. geothermal field. The new interpretation shows a qualitative agreement with the core-complex-related heat sourcing, as well as the fault-controlled reservoir compartments, impacting the efficient extraction of the thermal waters, in terms of quantity, quality and water temperature.

Interaction between medium-long period waves and smoothed mound breakwater with crown wall based on experiments and multi-phase simulations

Laboratory and numerical investigations of the wave force during the interaction between medium-long period waves and a smooth mound breakwater with crown wall were conducted. Multi-phase smoothed particle hydrodynamic model and constraint interpolation profile model were used and verified. A comparison of the pressure peaks shows that the accuracies of the two models are similar. A new formula is presented to estimate the wave force on the crown wall under medium-long period waves. With an increase in the wave period, the pulsating force on the crown wall gradually occupies the main component. The wave force on the slope increases with an increase in the wave period. The slope wave force with crown wall was compared to that without crown wall. The crown wall had little effect on the slope wave force. The Neelamani method overestimated the slope wave force. A new prediction method is proposed to significantly improves accuracy.

Hydrodynamics as a hidden abiotic factor constraining Ordovician chitinozoan morphological evolution

The Great Ordovician Biodiversification Event (GOBE) was one of the most important macro-evolutionary events of the early Paleozoic, and involved diversification of several planktic groups. Although hydrodynamics must have affected the evolution of these groups, it is difficult to establish causality with confidence. Chitinozoans, mysterious fossils with simple morphology and biostratigraphic utility, underwent great morphological innovations and adaptions through the Ordovician Period, and thus are especially suitable for exploring the effects of hydrodynamics on morphological diversification. We constructed simplified computer models of 92 Ordovician chitinozoan species from major paleoplates to assess the long-term changes in hydrodynamic properties (outer-wall pressure fields and velocity fields) by using computational fluid dynamics. The pressure difference between both ends of the chitinozoan vesicle is suggested to represent the floating ability of the chitinozoan. During the Ordovician, the pressure difference exhibited diachronous fluctuations in different families and on different paleoplates. A continuous increasing passive floating ability was achieved by the Desmochitinidae since the beginning of Ordovician. This evolutionary tendency is consistent with the previously suggested planktonic diversity increase during the GOBE, which initiated since the earliest Ordovician and indicates that the GOBE involved both long-termed taxonomic and morphological radiations. The low-velocity region at the antiapertural part of the vesicle in both individual and chain-structured chitinozoans supports the hypothesis that chitinozoans are independent protists, rather than metazoan eggs. We also analyzed how the evolution of structural innovations, such as chamber shape, neck length, carina length, and ornamentation arrangement, were influenced by hydrodynamics within individual lineages. The results show that several chitinozoan lineages evolved toward increased stability and better floating ability, indicating that convergent evolution in chitinozoans occurred as a result of hydrodynamic pressure. This study highlights the importance of hydrodynamic constraints for the evolution of Ordovician microplankton.

Transport phenomena in Darcy-Forchheimer flow over a rotating disk with magnetic field and multiple slip effects: modified Buongiorno nanofluid model

The current study focuses on investigating the significance of magnetic field and multiple slip constraints on the water-based graphene Darcy-Forchheimer nanofluid flow over a rotating disk. For a realistic approach, the modified Buongiorno nanofluid model that incorporates the combination of effective thermophysical properties, thermophoretic diffusion, and Brownian diffusion has been utilized. Engineering quantities like moment coefficient and pumping efficiency of the disk are also elucidated. The transmutation of the mathematically modeled nonlinear equations into a system of first-order ODEs are achieved through Von Kármán’s similarity transformations and are then resolved using the shooting technique along with the Runge–Kutta-Fehlberg algorithm. The highest heat transfer rate is experienced for smaller values of magnetic field parameter, Forchheimer number, porosity parameter, and thermal slip constraint. An increment rate of 88.14355% in the azimuthal drag coefficient and a decrement rate of 39.849732% in the radial drag coefficient are noted when the values of hydrodynamic slip constraint are augmented. Further, per unit increase in the volume fraction of graphene nanoparticles descends the moment coefficient and the entrainment velocity by 456.25501% and 12.48875%, respectively. The tidings of this numerical simulation have applications in spin coating, centrifugal filtration, medical equipment, gas turbine rotors, and thermal power generating systems.

Hydrodynamic constraint loads estimation on connectors of column-pontoon type very large floating structure (CP-VLFS) under wave stimulation

Column-pontoon type very large floating structure (CP-VLFS) operated at the deep and sea faraway areas are generally exposed to the extremely complex wave conditions. The connectors of CP-VLFS are generally subjected to complicated hydrodynamic constraint loads when the modules of CP-VLFS are stimulated by the long-tern wave forces. The general method for analyzing the hydrodynamic performances for marine floating structures and their components is almost on the basis of potential flow/fluid theory (PFT), but its algorithm principle is relatively complex and would consume plenty of computing time. During the preliminary design and scheme comparison stages for CP-VLFSs, the hydrodynamic results for CP-VLFSs’ modules and their connectors required to be rapidly determined. Hence, a rapid and high-efficiency estimating method for time-domain hydrodynamic constraint loads of connectors on CP-VLFS considering the mathematical and mechanical model of rigid module and flexible connector (RMFC) is developed via this paper. During this estimation method, the Morison theory of floating body is employed to assess the hydrodynamic excitation forces by random and irregular wave (RIW) on CP-VLFS structures, and a series of concise formulas for estimating the hydrodynamic constraint loads of CP-VLFS connectors are derived based on the geometrical relationship of the CP-VLFS modules’ motion. For this paper’s explorations, a three-module CP-VLFS model is considered as a case, and the time-domain hydrodynamic constraint loads of CP-VLFS’s connectors are determined under the RIW stimulations with different wave angles. Hydrodynamic constraint loads of CP-VLFS connectors estimated by this paper agree well with the results of PFT and those of physical experiment, validation the methodologies developed by this paper. Some useful conclusions may provide significant technical supports for hydrodynamic characteristics of CP-VLFS modules and their connectors optimization.

Construction of sea surface current vectors using a single HF radar: A theoretical study.

A technique called the stream and potential function method (SPFM) is presented to retrieve the sea surface current vector field from the radial-component measurements of only one high-frequency (HF) radar. SPFM estimates the surface current vector field jointly based on hydrodynamic constraints and a two-dimensional (2D) ocean current model. The current vector field is assumed to comprise two parts: nondivergent vortex flow and irrotational divergent flow; this guarantees that both the stream function and the potential function are considered. Physically, SPFM is embedded in a more physically consistent hydrodynamic framework that enables the spatiotemporal distribution characteristics of the current vector field at the sea surface to be effectively captured by a single HF radar. The evaluation of SPFM with HYCOM surface current dataset verifies that this approach is more reliable than the stream function method (SFM).

Streamlines Based Stochastic Methods and Reactive Transport Simulation Applied to Resource Estimation of Roll-Front Uranium Deposits Exploited by In-Situ Leaching

Roll-front uranium deposits are ore mineralizations that occur in sandstones or arkoses downstream from redox fronts or reduced/oxidized geochemical barriers. They are often bounded above and below by impermeable shaly/muddy layers making them ideal for in-situ leaching exploitation. Several stochastic simulations were previously investigated either to characterize the ore grade distribution within roll-front type deposits, or for describing geological processes involved in their formation. This work suggests some modifications/improvements of conventional geostatistical algorithms for honoring hydrodynamic constraints that govern fluid flows in ore bearing layers. In particular, instead of using the classical Euclidian or curvilinear (for Sgrid) distance for computing the variogram, it is proposed to calculate the variogram accounting for the time of flight (TOF) of water particles down the streamlines together with available well data. Non-deterministic streamline-based methods seem to provide more accurate interpolation results and resource estimation compared to a traditional geostatistical approach when applied to roll-front deposits.

A probabilistic risk-averse approach for energy storage sizing in all-electric ship

In recent years, energy storage systems (ESS) are becoming an integral part of modern all-electric ships (AES). The topic of optimal ESS sizing is important as it determines the cost and effectiveness of the vessel operation. Conventional ESS sizing only considers the investment stage and ignores the operation stage and uncertainties. This research work adopts a risk-averse approach by coordinating investment and operation stages. The proposed two-stage method ensures optimal operation by reducing cost and emission while addressing the stochasticity present in voyage planning. Firstly, multi-objective ESS sizing and energy management scheduling are jointly optimized by considering the operation and sizing objectives with the probabilistic hydrodynamic data-oriented constraints from the voyage scenarios. In the second stage, the information-gap decision (IGD) decides the number of modules and configuration of the ESS to achieve power and energy requirements. Various ESS technologies and numerous scenarios are used to verify the effectiveness of the proposed strategy. The results indicate the validity and requirement of the proposed method.

Regression analysis on MHD Darcy-Forchheimer hybrid nanoliquid flow over an elongated permeable sheet in a porous medium with hydrodynamic slip constraint: a realistic two-phase modified Buongiorno model

Injection and suction effects play a crucial role in astronomical disciplines, fuel injection, solar collector plate, thermal protection, and aerodynamics. Therefore, the dynamics of hydromagnetic Darcy-Forchheimer hybrid nanoliquid flow over an elongated permeable sheet in the presence of hydrodynamic slip and Newtonian boundary constraints is investigated. A realistic model considering the passive control of nanoparticles and the modified Buongiorno nanoliquid model has been utilised. The modelled partial differential equations are transmuted into a system of nonlinear ordinary differential equations with the aid of apposite similarity transformations which are then resolved numerically using the finite-difference based bvp5c routine. Regression analysis is employed to statistically scrutinise the relationship between the pertinent parameters and the drag coefficients. It is observed that the -directional velocity descends with the Forchheimer number and hydrodynamic slip parameter whereas the -directional velocity ascends with the stretching parameter. It is also noted that the Biot number and the volume fraction of copper nanoparticles have a constructive effect on the hybrid nanoliquid temperature. Furthermore, lower temperature and velocity profiles were exhibited by the suction case when compared with the injection case. An improved heat transfer rate is observed for higher values of Biot number and volume fraction of copper nanoparticles.

Large size in aquatic tetrapods compensates for high drag caused by extreme body proportions

Various Mesozoic marine reptile lineages evolved streamlined bodies and efficient lift-based swimming, as seen in modern aquatic mammals. Ichthyosaurs had low-drag bodies, akin to modern dolphins, but plesiosaurs were strikingly different, with long hydrofoil-like limbs and greatly variable neck and trunk proportions. Using computational fluid dynamics, we explore the effect of this extreme morphological variation. We find that, independently of their body fineness ratio, plesiosaurs produced more drag than ichthyosaurs and modern cetaceans of equal mass due to their large limbs, but these differences were not significant when body size was accounted for. Additionally, necks longer than twice the trunk length can substantially increase the cost of forward swimming, but this effect was cancelled out by the evolution of big trunks. Moreover, fast rates in the evolution of neck proportions in the long-necked elasmosaurs suggest that large trunks might have released the hydrodynamic constraints on necks thus allowing their extreme enlargement.

Hydrodynamic constraints on the energy efficiency of droplet electricity generators

Electric energy generation from falling droplets has seen a hundred-fold rise in efficiency over the past few years. However, even these newest devices can only extract a small portion of the droplet energy. In this paper, we theoretically investigate the contributions of hydrodynamic and electric losses in limiting the efficiency of droplet electricity generators (DEG). We restrict our analysis to cases where the droplet contacts the electrode at maximum spread, which was observed to maximize the DEG efficiency. Herein, the electro-mechanical energy conversion occurs during the recoil that immediately follows droplet impact. We then identify three limits on existing droplet electric generators: (i) the impingement velocity is limited in order to maintain the droplet integrity; (ii) much of droplet mechanical energy is squandered in overcoming viscous shear force with the substrate; (iii) insufficient electrical charge of the substrate. Of all these effects, we found that up to 83% of the total energy available was lost by viscous dissipation during spreading. Minimizing this loss by using cascaded DEG devices to reduce the droplet kinetic energy may increase future devices efficiency beyond 10%.

Inversion of the Degradation Coefficient of Petroleum Hydrocarbon Pollutants in Laizhou Bay

When petroleum hydrocarbon pollutants enter the ocean, besides the migration under hydrodynamic constraints, their degradation due to environmental conditions also occurs. However, available observations are usually spatiotemporally disperse, which makes it difficult to study the degradation characteristics of pollutants. In this paper, a model of transport and degradation is used to estimate the degradation coefficient of petroleum hydrocarbon pollutants with the adjoint method. Firstly, the results of a comprehensive physical–chemical–biological test of the degradation of petroleum hydrocarbon pollutants in Laizhou Bay provide a reference for setting the degradation coefficient on the time scale. In ideal twin experiments, the mean absolute errors between observations and simulation results obtain an obvious reduction, and the given distributions can be inverted effectively, demonstrating the feasibility of the model. In a practical experiment, the actual distribution of petroleum hydrocarbon pollutants in Laizhou Bay is simulated, and the simulation results are in good agreement with the observed ones. Meanwhile, the spatial distribution of the degradation coefficient is inverted, making the simulation results closer to the actual observations.

Hydrodynamic Constraints on Ore Formation by Basin‐Scale Fluid Flow at Continental Margins: Modelling Zn Metallogenesis in the Devonian Selwyn Basin

AbstractThe clastic‐dominant (CD‐type) deposits that are contained within sedimentary basins are major resources of Zn, Pb and Ag, but their formation by basin‐scale hydrothermal mass and energy transport processes is still poorly understood. Using geological constraints from the Late Devonian Selwyn Basin (Canada), we apply quantitative numerical fluid flow modeling to explore the effect of strata permeability, timing of fault opening and increased heat flow in controlling fluid migration, metal leaching and ore formation during an extensional tectonic event. The results indicate that tapping hot fluids from a confined and permeable aquifer at several km depths by means of permeable normal faults is a key factor for the formation of large Zn‐Pb deposits. The hot (282°C) ore‐forming fluids are transported to the shallow subsurface shortly after the initiation of a rifting event (within 100 kyr), before the development of extensive basin‐scale convection patterns that lead to stronger cooling and a reduction in the capacity of the hydrothermal system to make an economic deposit. Such a hydrothermal event can result in metal endowments comparable to the deposits of the Selwyn Basin.

The ecohydrological impact of water resource developments through inundation regime analysis of a large semi-arid floodplain

The ephemeral inundation of floodplains in semi-arid and arid zone climates is an essential driver of biological productivity. Natural biota depend on floodplain inundation to support critical reproductive life phases. In historical times, grazing industries have developed taking advantage of phases of high productivity associated with the overbank flow. However, the modelling of inundation in lowland floodplains is challenged by the complexity of topographic and hydrodynamic constraints. Here we apply a spatially explicit fine-scale inundation model to compare floodplain inundation regimes associated with current hydrological development on the Darling River floodplain, Australia, and pre-development, conceptualised as the removal of hydrological control structures. Our results suggest that hydrological developments in the Darling River catchment have substantially increased inter-flood period, an effect particularly pronounced during dry climatic phases. The result explains the decline in waterbird utilisation in this section of the Darling River, the low resilience of outer floodplain vegetation to the recent drought, and the reduction in grazing capacity. Water resource development had less impact on large inundation events.