Three-dimensional Navier-Stokes Equations Research Articles

Localization of Beltrami fields: Global smooth solutions and vortex reconnection for the Navier-Stokes equations

We introduce a class of divergence-free vector fields on R3 obtained after a suitable localization of Beltrami fields. First, we use them as initial data to construct unique global smooth solutions of the three dimensional Navier-Stokes equations. The relevant fact here is that these initial data can be chosen to be large in any critical space for the Navier–Stokes problem, however they satisfy the nonlinear smallness assumption introduced in [10]. As a further application of the method, we use these vector fields to provide analytical example of vortex-reconnection for the three-dimensional Navier-Stokes equations on R3. To do so, we exploit the ideas developed in [13] but differently from this latter we cannot rely on the non-trivial homotopy of the three-dimensional torus. To overcome this obstacle we use a different topological invariant, i.e. the number of hyperbolic zeros of the vorticity field.

Temporal consistency loss for physics-informed neural networks

Physics-informed neural networks (PINNs) have been widely used to solve partial differential equations (PDEs) in a forward and inverse manner using neural networks. However, balancing individual loss terms can be challenging, mainly when training these networks for stiff PDEs and scenarios requiring enforcement of numerous constraints. Even though statistical methods can be applied to assign relative weights to the regression loss for data, assigning relative weights to equation-based loss terms remains a formidable task. This paper proposes a method for assigning relative weights to the mean squared loss terms in the objective function used to train PINNs. Due to the presence of temporal gradients in the governing equation, the physics-informed loss can be recast using numerical integration through backward Euler discretization. The physics-uninformed and physics-informed networks should yield identical predictions when assessed at corresponding spatiotemporal positions. We refer to this consistency as “temporal consistency.” This approach introduces a unique method for training physics-informed neural networks (PINNs), redefining the loss function to allow for assigning relative weights with statistical properties of the observed data. In this work, we consider the two- and three-dimensional Navier–Stokes equations and determine the kinematic viscosity using the spatiotemporal data on the velocity and pressure fields. We consider numerical datasets to test our method. We test the sensitivity of our method to the timestep size, the number of timesteps, noise in the data, and spatial resolution. Finally, we use the velocity field obtained using particle image velocimetry experiments to generate a reference pressure field and test our framework using the velocity and pressure fields.

Performance improvement of a rotating gas separator for electrical submersible pump considering entropy generation method

The utilization of Electrical Submersible Pumps (ESPs) stands as one of the foremost methods in artificially extracting oil, primarily within the oil industry. Under typical conditions, the pump encounters a two-phase flow of oil and gas. Should the gas phase within this mixture surpass an acceptable threshold, it can lead to a significant decline in performance and inflict detrimental damage upon the pump. To address this issue, the incorporation of a gas separator unit, one of the pivotal components within ESPs, is imperative at the pump's inlet section. Enhancing the gas separator unit holds paramount importance for ensuring pump safety and optimizing performance, particularly in wells with elevated gas contents.The conventional approach to calculating hydraulic losses in turbomachinery, relying on pressure drop calculations, often falls short in pinpointing the precise locations of losses. This paper delves into enhancing gas separator performance by augmenting gas separation efficiency through the application of the entropy generation method and leveraging the second law of thermodynamics. To achieve this, pivotal entropy-generating geometrical parameters of the gas separator were identified as the design variables necessary for forming the Taguchi sample space. Numerical simulations were conducted utilizing steady three-dimensional Reynolds-Averaged Navier-Stokes (RANS) equations for incompressible fluid flow, coupled with a turbulence model. Results indicate that the gas separation efficiency (GSE) of the initial model surged from 45.6% to 88% in the improved sample, albeit with a concurrent rise in entropy generation rate (EGR) from 209 W/K to 243.1 W/K. To establish a more comprehensive criterion for analysis, the ratio of GSE to EGR was employed as an objective function. This ratio quantifies the efficiency of gas separation per unit of energy loss, and it escalated from 0.218 in the primary sample to 0.362 in the improved sample, representing a 66% increase. This signifies that despite simultaneous increases in EGR and GSE, the rate of energy loss per unit of gas separation has diminished. Furthermore, the heightened EGR in the improved sample can be attributed to an increase in total volume, leading to an expanded contact surface area and consequently an elevation in total entropy. This investigation underscores the advantages of the entropy generation method, particularly in delineating the precise location and magnitude of energy dissipation within the rotating gas separator.

Boundary feedback control of Navier–Stokes equations around arbitrary bluff body with prescribed drag and lift coefficients

This paper presents a boundary feedback control method for the two- and three-dimensional Navier–Stokes equations around an arbitrary bluff body, with prescribed drag and lift coefficients. In order to determine the feedback control law, we consider an extended system coupling the equations governing the Navier–Stokes problem with an equation satisfied by the control on the bluff body, which is a part of the domain boundary. We utilize the artificial compressibility method, which approximates the Navier–Stokes equations in the limit, along with a priori estimation techniques, to establish a boundary control. Such a control law ensures that the prescriptions of the drag and lift coefficients are attained. Subsequently, a compactness result allows to let the compressibility parameter tend to zero. The application of the Faedo-Galerkin method is essential in reaching this result.

Vortex breakdown in the small Mach number regimes

The effect of compressibility for flow inside the cylinder with the top rotating lid (Vogel-Escudier flow) is examined. Three-dimensional Navier–Stokes equations for compressible flow in Cartesian coordinates are used to simulate the flow using open-source OpenFOAM software. The Mach number (Ma) of the flow is varied from 0.1 to 0.3, and the Reynolds number (Re) is varied from 1000 to 5000 for a fixed aspect ratio (Γ = 2.5) of the cylinder. The flow is found to have a transition from a steady axisymmetric state to a non-axisymmetric state exhibiting multiple azimuthal waves as the Mach number and the Reynolds number are varied. The flow field changes significantly with an increase in Ma for unsteady flow at higher Re. An increase in Ma increases the side wall azimuthal instability, as found in the perturbation contour plots and time series analysis. Further, we reconstruct phase portraits to show the dynamics of the flow finally becoming chaotic as the Reynolds number is increased to 5000. Finally, we support the argument with Lyapunov exponents for the higher Re samples. The Lyapunov Exponent is found to increase with Ma.

Optimizing Infragravity Wave Attenuation to Improve Coral Reef Restoration Design for Coastal Defense

Coral reefs are effective natural flood barriers that protect adjacent coastal communities. As the need to adapt to rising sea levels, storms, and environmental changes increases, reef restoration may be one of the best tools available to mitigate coastal flooding along tropical coastlines, now and in the future. Reefs act as a barrier to incoming short-wave energy but can amplify low-frequency infragravity waves that, in turn, drive coastal flooding along low-lying tropical coastlines. Here, we investigate whether the spacing of reef restoration elements can be optimized to maximize infragravity wave energy dissipation while minimizing the number of elements—a key factor in the cost of a restoration project. With this goal, we model the hydrodynamics of infragravity wave dissipation over a coral restoration or artificial reef, represented by a canopy of idealized hemispherical roughness elements, using a three-dimensional Navier–Stokes equations solver (OpenFOAM). The results demonstrate that denser canopies of restoration elements produce greater wave dissipation under larger waves with longer periods. Wave dissipation is also frequency-dependent: dense canopies remove wave energy at the predominant wave frequency, whereas sparse canopies remove energy at higher frequencies, and hence are less efficient. We also identify an inflection point in the canopy density–energy dissipation curve that balances optimal energy losses with a minimum number of canopy elements. Through this work, we show that there are an ideal number of restoration elements per across-shore meter of coral reef flat that can be installed to dissipate infragravity wave energy for given incident heights and periods. These results have implications for designing coral reef restoration projects on reef flats that are effective both from a coastal defense and costing standpoint.

Global regularity and decay behavior for Leray equations with critical-dissipation and its application to self-similar solutions

In this paper, we show the global regularity and the optimal decay of weak solutions to the generalized Leray problem with critical dissipation. Our approach hinges on the maximal smoothing effect, L p L^{p} -type elliptic regularity of linearization, and the action of the heat semigroup generated by the fractional powers of Laplace operator on distributions with Fourier transforms supported in an annulus. As a by-product, we construct a self-similar solution to the three-dimensional incompressible Navier-Stokes equations. Most notably, we prove the global regularity and the optimal decay without the need for additional requirements found in existing literatures.

Phase transitions in the fractional three-dimensional Navier–Stokes equations

The fractional Navier–Stokes equations on a periodic domain [0,L]3 differ from their conventional counterpart by the replacement of the −νΔu Laplacian term by νsAsu , where A=−Δ is the Stokes operator and νs=νL2(s−1) is the viscosity parameter. Four critical values of the exponent s⩾0 have been identified where functional properties of solutions of the fractional Navier–Stokes equations change. These values are: s=13 ; s=34 ; s=56 and s=54 . In particular: (i) for s>13 we prove an analogue of one of the Prodi–Serrin regularity criteria; (ii) for s⩾34 we find an equation of local energy balance and; (iii) for s>56 we find an infinite hierarchy of weak solution time averages. The existence of our analogue of the Prodi–Serrin criterion for s>13 suggests the sharpness of the construction using convex integration of Hölder continuous solutions with epochs of regularity in the range 0<s<13 .

Numerical research on the resonance frequency characteristics of the Sparkjet actuator using modal analysis

In this study, the resonance frequency characteristics of the SparkJet actuator are examined through numerical investigation using modal analysis. First, an eigenvalue problem is established to compute the resonance frequencies of the SparkJet actuator, considering its configuration, boundary conditions and internal physical phenomena. To validate the eigenvalue problem, computational fluid dynamics (CFD) simulation is conducted utilizing unsteady three-dimensional Navier-Stokes equations with plasma energy source term, assuming local thermal equilibrium (LTE). Subsequently, the resonance frequencies are obtained by performing fast Fourier transform (FFT) on the thrust and average pressure data obtained from the CFD. In our investigation of the resonance frequency characteristics, eigenmode decomposition on the pressure contour obtained from the CFD is conducted utilizing the eigenfunctions obtained from the eigenvalue problem and their orthogonality. The eigenmode decomposition enables us to quantitatively evaluate the contribution of each eigenfunction to the thrust. Comparisons between the frequencies corresponding to the eigenfunctions significantly influencing on the thrust and the resonance frequencies obtained by FFT reveal a maximum error of 5.29 % and an average error of 2.35 % Moreover, when the taper angle is relatively large (approximately 45∘ or more), eigenfunctions significantly influencing on the thrust can be categorized into two distinct geometric patterns. These physically represent the waves that propagate and reflect in the streamwise or radial direction within the SparkJet actuator. This observation implies that the complex interactions of shock waves within the SparkJet actuator can be reduced to a few waves with simple physical interpretations. This may potentially aid in analyzing the physical phenomena within the SparkJet actuator.

Drift and afterburning effect on rocket exhaust plume impingement and optimization of deflector

This paper studies the one-nozzle liquid rocket exhaust plume impinging on the flame deflector. The effect of drift and afterburning on exhaust plume impinging on the deflector during the takeoff phase is studied by numerical simulation. An impact model is established based on three-dimensional compressible Navier-Stokes equations, a two-equation realizable k-epsilon turbulence model, an afterburning model, and second-order total variation diminishing upwind scheme. The study shows that the smoothness of the deflector discharge is affected by the impingement position of the exhaust plume impinging on the deflector due to the drift of such a position during the take-off phase of the rocket. The temperature of the rocket exhaust plume flow field after considering the chemical reactions is higher than that of the frozen flow, and the temperature of the deflector surface is also higher than that of the frozen case. With the increase of the impingement angleat inlet areaof the rocket exhaust plume impinging on the deflector, the deflector discharge performance gradually decreases. At the same impingement angleat inlet area, as the impingement angleat exit areadecreases, the deflector slot discharges more smoothly.

A high-order sharp-interface immersed boundary solver for high-speed flows

A sharp-interface immersed boundary (IB) solver for the three-dimensional compressible Navier-Stokes equations with shock discontinuities is presented. The IB method is based on high-order schemes and a ghost-cell method which uses Taylor polynomial interpolation and weighted least-squares error minimization to impose the boundary conditions on the immersed boundary. The results show that the method enables robust and accurate calculation of high-speed flow problems involving complex geometries, moving boundaries, and solid and membrane geometries. Third-order accuracy or higher is maintained even for supersonic conditions. The numerical framework is validated through several two-dimensional and three-dimensional benchmark problems at subsonic and supersonic speeds. Additionally, the method is demonstrated for airfoil dynamic stall and wing-store interaction investigations.

Stationary and Non-Stationary Periodic Flows Mathematical Modelling using Various Vortex Viscosity Models

Introduction. Mathematical modelling of currents is an urgent research topic in the field of hydrodynamics and oceanography. Despite ongoing research in the field of developing accurate and efficient numerical methods for solving Navier-Stokes equations that take into account vortex viscosity, the problems of accurate prediction and control of turbulence remain unresolved. The influence of nonlinear effects in vortex viscosity models on the accuracy of forecasts and their applicability to various flow conditions also remains relevant. The aim of the study is to study the influence of linearized and quadratic bottom friction and two turbulence models on the numerical solution of stationary and non-stationary periodic flows. Special emphasis is placed on comparing numerical results with analytical solutions within the framework of using various models of bottom friction.Materials and Methods. The computational models used in this study are based on a simplified two-dimensional wave model and full three-dimensional Navier-Stokes equations. The classical model of shallow water motion and the 2D model without taking into account dynamic changes in the geometry of the reservoir surface are derived from a system of equations for a spatially inhomogeneous three-dimensional mathematical model of wave hydrodynamics of a shallow reservoir. Analytical solutions were found by linearization of the equations, which obviously has its limitations. A distinction is made between two types of nonlinear effects – nonlinearities caused by higher-order terms in the equations of motion, i. e. terms of advective acceleration and friction, and nonlinear effects caused by geometric nonlinearities, this is due, for example, to different water depths and reservoir widths, which will be important when modelling a real sea.Results. The results of modeling stationary and non-stationary periodic flows in a schematized rectangular basin using linearized bottom friction are presented. The influence of linearization on the numerical solution is investigated in comparison with analytical profiles using models calculating bottom friction in a quadratic formulation. In combination with quadratic bottom friction, two turbulence models are studied: the constant vortex viscosity and the Prandtl mixing length model. The results obtained as a result of three-dimensional modelling are compared with the results of two-dimensional modeling and analytical solutions averaged in depth.Discussion and Conclusion. New approaches to modelling and studying flows with variable vortex viscosity are proposed, including analysis of the influence of linearization and the use of various turbulence models. For the linearized and quadratic formulations of bottom friction, it is proved that the numerical results for the case of stationary flow show great similarity with analytical solutions, since the surface height is much less than the water depth and advection can be neglected. The numerical results for the unsteady flow also show a good agreement with the theory. Unlike analytical solutions, numerical modelling has minor deviations in the long run. The study of flows, within the framework of using various turbulence models, will make it possible to take into account the influence of nonlinear effects in vortex viscosity models on the accuracy of forecasts and their applicability to various flow conditions. The results obtained make it possible to better understand and describe the physical processes occurring in shallow waters. This opens up new possibilities for applying mathematical modelling to predict and analyze the impact of human activities on the marine environment and to solve other problems in the field of oceanology and geophysics.

Existence of global solution to 3D density-dependent incompressible Navier-Stokes equations

&lt;abstract&gt;&lt;p&gt;In this article, we are committed to studying the three-dimensional incompressible Navier-Stokes equations, where the viscosity depends on density according to a power law. We investigate the Cauchy problem by constructing an approximated solution and bootstrap argument. Finally, we establish the existence of a global strong solution under the conditions of small initial data and the compatibility condition. Meanwhile, the algebraic decay-in-time rates for the solution are also obtained. It is worth pointing out that the degradation of viscosity is allowed.&lt;/p&gt;&lt;/abstract&gt;

Floquet-based analysis on three-dimensional non-axisymmetric instabilities in oscillatory-driven Taylor–Couette flows and their low-frequency asymptotic behavior using Wentzel–Kramers–Brillouin method

This paper revisits the linear stability analysis of oscillatory-driven flows between two oscillating cylinders against non-axisymmetric disturbances. This study is motivated by the lack of a sufficiently reliable theoretical analysis giving insight into the experimentally observed spiral-like non-axisymmetric patterns when the cylinders are counter-oscillating. A new generalized time-dependent algebraic eigenvalue problem is constructed from the linearized set of the three-dimensional Navier–Stokes equations around the purely azimuthal basic state. Numerical evaluation of the critical eigenvalues combining both Floquet theory and spectral method reveals the existence of frequency ranges where this basic state becomes unstable against three-dimensional non-axisymmetric disturbances before it does so for two-dimensional axisymmetric ones. Indeed, as the oscillation frequency of the cylinders increases, the azimuthal wave number of the critical eigensolution is found to change from 0 to 2 to 1 and then back to 0. The primary bifurcation exchange between two instability modes with different azimuthal wave numbers occurs via different types of codimension-2 bifurcation points giving rise to discontinuities in the critical axial wave number where reversing and non-reversing non-axisymmetric Taylor vortex flows are identified. In addition, by extending our numerical calculations to the co-oscillating case, we show that the axisymmetric disturbances are the most unstable confirming thus existing experimental findings. Furthermore, a Wentzel–Kramers–Brillouin (WKB) analysis is performed to shed light on the asymptotic behavior of these time-dependent flows in the low-frequency limit when the cylinders are slowly oscillating.

Heat transfer enhancement of supercritical carbon dioxide in eccentrical helical tubes

A type of eccentrical helical tube (EHT) was proposed for more efficient and compact supercritical carbon dioxide (SCO2) heat exchangers in refrigeration systems. The forced convective heat transfer of SCO2 flowing in three designed eccentrical helical tubes with pitches of 25, 50 mm and eccentricities of 0.9, 1.5 mm was simulated by using the three-dimensional steady Reynolds-averaged Navier-Stokes equations, shear stress transport turbulence model and energy equation in ANSYS CFX 2019 R2 at mass fluxes of 200, 400 kg/m2s, inlet pressures of 8, 9 MPa, outwards wall heat fluxes of 12, 24 kW/m2. The flow and heat transfer models were validated in the plain tube with experimental mean heat transfer coefficient and empirical Darcy friction factor. Influences of pitch, eccentricity and operational conditions on heat transfer enhancement were identified. Flow pattern, heat transfer mechanism and vortex kinematics were clarified. Heat transfer enhancement of SCO2 in the EHT was compared with water and air in the EHT, twisted elliptical tube and conical tube, respectively. A pitch of 25 mm and eccentricity of 1.5 mm at 6 mm tube diameter can achieve a better thermal-hydraulic performance. A higher SCO2 mass flux raises Nusselt number and reduces friction factor, a higher inlet pressure and a larger wall heat flux reduces Nusselt number but increases friction factor. The ratio f/f0 is ranged in 2.52–1.68 and drops off with increasing inlet pressure and nominal Reynolds number, the ratios Nu/Nu0, ψ and η curves show a concave shape near the pseudocritical point ranged in 1.68–1.06 and 1.06–1.55, 1.23–0.83 and 0.83–1.30, 0.67–0.50 and 0.50–0.92 at the pitch of 25 mm and eccentricity of 1.5 mm, inlet pressure of 8 MPa, mass flux of 400 kg/m2s, and wall heat flux of 12 kW/m2. A helical flow pattern with a core flow occurs in the EHT, the local heat transfer coefficient can be correlated to absolute helicity. The high-wall shear stress on the ridge of the EHT is responsible for the heat transfer enhancement. The f/f0 value of the EHT is in between the twisted elliptical tube and the conical tube, but the Nu/Nu0 and ψ values are comparable.

Performance and wake interaction between two aligned vertical axis turbines

Performance and wake interaction between two aligned vertical turbines are investigated by solving the three-dimensional Navier-Stokes equations with the k−ω SST IDDES turbulence model. Specifically, the impact of longitudinal spacing between the upstream and downstream turbines is examined. The numerical results show that as the longitudinal distance increases, the performance of the downstream turbine shows a quadratic growth. This is phenomenon is strongly correlated to the wake recovery of the upstream turbine. Based on the velocity and turbulence distribution, the wake of the upstream turbine could be divided into three distinct zones. However, the zone characterized by low axial velocity and turbulence level is not observed in the wake of the downstream turbine. This difference primarily arises from the high turbulence present in the incoming wake from the upstream turbine, combined with the turbulence generated by the downstream turbine. Interestingly, regardless of the longitudinal distances between the turbines, the downstream turbine displays similar wake patterns for different streamwise distances between turbines. This consistency is attributed to the influence of the upstream turbine's wake on the stability of the downstream turbine's wake. The downstream turbine is suggested to be positioned in the zone where the upstream turbine's wake has fully developed.

Study of the blood flow structure in personalized models of graft branch from the femoral artery

The paper presents the methodology and results of calculating the pulsating flow of blood-mimicking fluid in three personalized models of proximal anastomosis of the femo-ral artery after femoral popliteal bypass surgery performed using synthetic grafts. Per-sonalized models were built based on computed tomography data and ultrasound meas-urements of blood flow velocity in the common femoral artery and in the graft. The char-acteristics of the pulsating flow of blood-mimicking fluid were calculated by numerically solving the three-dimensional unsteady Navier-Stokes equations. Comparison of the calculated velocity field obtained for one of the personalized models with clinical meas-urement data using ultrasonic high-speed vector imaging (applying the V Flow technol-ogy implemented in the Mindray scanner) showed satisfactory agreement of the results. A comparative analysis of the flow structure in two personalized models built for the sec-ond patient one and seven months after surgery is given. It was established that the nar-rowing of the flow sections of the vascular bed, detected after seven months, due to the growth of neointima in the common femoral artery (immediately before the anastomosis) and in the initial section of the graft, led to a significant increase in gradients of the ve-locity field and the time-averaged wall shear stress (TAWSS) in the area of the anastomo-sis; at the same time, the value of the oscillatory shear index (OSI) on the wall throughout the entire anastomosis area decreased. It was also revealed that at a distance of several calibers from the anastomosis, a single-vortex, weakly swirling flow is formed in the graft, the direction of swirl in which is determined by the individual geometry of the anastomo-sis area.

Numerical Investigation of Odor-Guided Navigation in Flying Insects: Impact of Turbulence, Wingbeat-Induced Flow, and Schmidt Number on Odor Plume Structures.

Odor-guided navigation is fundamental to the survival and reproductive success of many flying insects. Despite its biological importance, the mechanics of how insects sense and interpret odor plumes in the presence of complex flow fields remain poorly understood. This study employs numerical simulations to investigate the influence of turbulence, wingbeat-induced flow, and Schmidt number on the structure and perception of odor plumes by flying insects. Using an in-house computational fluid dynamics solver based on the immersed-boundary method, we solve the three-dimensional Navier-Stokes equations to model the flow field. The solver is coupled with the equations of motion for passive flapping wings to emulate wingbeat-induced flow. The odor landscape is then determined by solving the odor advection-diffusion equation. By employing a synthetic isotropic turbulence generator, we introduce turbulence into the flow field to examine its impact on odor plume structures. Our findings reveal that both turbulence and wingbeat-induced flow substantially affect odor plume characteristics. Turbulence introduces fluctuations and perturbations in the plume, while wingbeat-induced flow draws the odorant closer to the insect's antennae. Moreover, we demonstrate that the Schmidt number, which affects odorant diffusivity, plays a significant role in odor detectability. Specifically, at high Schmidt numbers, larger fluctuations in odor sensitivity are observed, which may be exploited by insects to differentiate between various odorant volatiles emanating from the same source. This study provides new insights into the complex interplay between fluid dynamics and sensory biology and behavior, enhancing our understanding of how flying insects successfully navigate using olfactory cues in turbulent environments.

Wings and whiffs: Understanding the role of aerodynamics in odor-guided flapping flight

Odor-guided navigation is an indispensable aspect of flying insects' behavior, facilitating crucial activities such as foraging and mating. The interaction between aerodynamics and olfaction plays a pivotal role in the odor-guided flight behaviors of insects, yet the interplay of these two functions remains incompletely understood. In this study, we developed a fully coupled three-way numerical solver, which solves the three-dimensional Navier–Stokes equations coupled with equations of motion for the passive flapping wings, and the odorant advection–diffusion equation. This numerical solver is applied to investigate the unsteady flow field and the odorant transport phenomena of a fruit fly model in odor-guided upwind surge flight over a broad spectrum of reduced frequencies (0.325–1.3) and Reynolds numbers (90–360). Our results uncover a complex dependency between flight velocity and odor plume perception, modulated by the reduced frequency of flapping flight. At low reduced frequencies, the flapping wings disrupt the odor plume, creating a saddle point of air flow near the insect's thorax. Conversely, at high reduced frequencies, the wing-induced flow generates a stagnation point, in addition to the saddle point, that alters the aerodynamic environment around the insect's antennae, thereby reducing odor sensitivity but increasing the sampling range. Moreover, an increase in Reynolds number was found to significantly enhance odor sensitivity due to the synergistic effects of greater odor diffusivity and stronger wing-induced flow. These insights hold considerable implications for the design of bio-inspired, odor-guided micro air vehicles in applications like surveillance and detection.

Analysis of the calibration and validation of hydrodynamic simulations with TELEMAC-3D model of the Patos Lagoon

This work presents the analysis of the calibration and validation of the computational model for two configurations of the Jetties of the Rio Grande Barra for hydrodynamic studies of the Patos Lagoon and the continental shelf of southern Brazil. The model used was TELEMAC-3D, which solves the three-dimensional Navier-Stokes equations, considering the hydrostatic hypothesis, to describe the dynamics of free surface geophysical fluids. We developed two finite element triangular meshes, with about 75.000 elements and seven sigma levels. The numerical domain reaches depths up to 2.427 m, with fluvial and oceanic liquid boundaries. The horizontal turbulence model adopted was Smagorinsky and the vertical model of mixing length. Current velocity data obtained from December 2005 were used for calibration, varying the coefficient of wind friction, horizontal and vertical velocity diffusion, and the salinity tracer. The coefficient of wind influence was the factor that most influenced the model results. The calculated Relative Mean Absolute Error was 0.383 dn. for surface and 0.167 dn. for depth, rated good and excellent, respectively. For validation, we evaluated the model performance on reproducing the salinity behavior, related to the depth of the environment, in January 2017. The calculated Root Mean Square Error was 7.37 dn. and the Relative Mean Absolute Error was 0.228 dn., rating the model performance as good. These variances between metrics is uniformly acceptable for real models. Salt transport is a complex phenomenon and depends on both advective and diffusive transport. Thus, it is possible to conclude that he proposed computational model is able to reproduce a complex phenomenon reliably.