Steady Fluid Research Articles

Application of vanishing diffusion stabilization in Oldroyd-B fluid flow simulations

Two different methods of artificial diffusion stabilization of the numerical simulations of steady Oldroyd-B fluids flows are presented. They are based on the idea of vanishing in time added stabilization terms which are only present during the initial stage of time-marching process towards the steady state solution. These extra terms naturally vanish and do not affect the final result. The numerical simulations are built on a simple steady 2D case of Oldroyd-B fluid flow in a symmetrical corrugated channel. Numerical solver uses finite element discretization in space and characteristic Galerkin method for pseudo-time discretization. Numerical results are presented in the form of isolines and graphs of selected flow variables, to assess the possible efficiency of the different stabilization techniques used.

V12-06 PATIENT INFORMATION VIDEO: SURGERY FOR NEUROGENIC BLADDER

You have accessJournal of UrologyCME1 Apr 2023V12-06 PATIENT INFORMATION VIDEO: SURGERY FOR NEUROGENIC BLADDER Anne Cameron, Victoria Norausky, Lanre Aboderin, and Iryna Crescenze Anne CameronAnne Cameron More articles by this author , Victoria NorauskyVictoria Norausky More articles by this author , Lanre AboderinLanre Aboderin More articles by this author , and Iryna CrescenzeIryna Crescenze More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003347.06AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Many patients with neurogenic lower urinary tract dysfunction (NLUTD) fail conservative management with oral agents and bladder botulinum toxin and require surgical intervention to treat their neurogenic detrusor overactivity related incontinence or poor bladder compliance. Patients need reliable, easy to understand information to help guide their decision. METHODS: This video was created as part of the neurogenic bladder series encompassing multiple related topics for this patient population. All information is intended to be used by patients and their advocates as well as health care providers. Multiple clinician’s consensus were utilized to generate the information deemed essential for patients to understand these choices. RESULTS: This short video outlines bladder issues that would lead to a patient and their provider choosing surgery to treat intractable bladder symptoms. Conservative management with steady fluid intake, urinary tract infection prevention and regular catheterization are first discussed followed by oral agents and bladder injections to treat incontinence and or poor bladder compliance. The pathophysiology of neurogenic detrusor overactive and its consequences are also explained. Augmentation cystoplasty is reviewed in detail as well as continent catheterizable channels and urinary diversion. Important postoperative expectations and complications are discussed as well as long term follow up plans. CONCLUSIONS: This video provides patient appropriate information on NLUTD related bladder dysfunction and counselling on possible surgical options for treating this disorder when it is refractory to conservative, medical and injection treatments. Source of Funding: Craig Nielsen Foundation © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e1066 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Anne Cameron More articles by this author Victoria Norausky More articles by this author Lanre Aboderin More articles by this author Iryna Crescenze More articles by this author Expand All Advertisement PDF downloadLoading ...

The magnetohydrodynamic flow of viscous fluid and heat transfer examination between permeable disks by AGM and FEM

This paper studied a two-dimensional steady, laminar, and incompressible viscous fluid between two porous disks in outer magnetic amplitude. The invention in this essay is broken down into two interconnected parts. In the first part, the dimensionless equations of the nanofluid flow passing between two disks are investigated using the Akbari-Ganji Method (AGM). The findings are compared with those obtained using the numerical method. In the second section, the Finite Element Method (FEM) in CFD software was used to analyze the fluid pressure, velocity, and temperature parameters of two MWCNT and SWCNT nanotubes. Sliding at the limits shifts the turning point toward the upper disc. It is observed that the magnitude of the axial velocity reduces as the Reynolds number increases at any point in the space between the discs. Two critical areas within the fluid locale where the fluid is persistent despite changes in significant parameters are uncovered by contrasts in radial velocity profiles. The heat transmission rate at the lower penetrable circle consistently diminishes within the nearness of slip as the Reynolds number increments. Also, the inverse is genuine at the upper permeable plate.

Steady and Time Dependent Study of Laminar Separation Bubble (LSB) behavior along UAV Airfoil RG-15

The flow around the Unmanned Arial Vehicle (UAV) operating at a low Reynolds number regime of the O() is predominantly laminar and it leads to the formation of Laminar Separation Bubble (LSB). The pressure, shear stress, and heat flux distribution are considerably affected by LSB, which affects lift, drag, and pitching moment values. Most existing RANS (Reynolds-Averaged Navier-Stokes) turbulence models are built on the assumption of fully turbulent flow. Therefore, these models require additional transport equations or reformulations or specific transition information to predict the LSB observed in low Reynolds number transition flows. Steady and transient computational fluid dynamics simulations were done using the RANS based transition turbulence model to study the behavior of LSB on UAV airfoil RG-15. The transition turbulence model can predict the LSB with considerable accuracy. The steady state and time averaged simulation results are matching in the pre stall region but deviates after stalling. High amplitude velocity fluctuations were observed near regions of transition and separation.

Numerical simulation of airflow field in rotor spinning channel based on dynamics optimization

To respond to high-speed characteristics and complicated airflow of the air-extraction rotor, the paper takes advantage of ANSYS parametric design language to develop the parametric finite element modeling program by taking the geometric feature of the slip plane as the design variable, so as to propose a mathematical model applicable to dynamics optimization of the rotor. The optimal design parameters of the slip plane are obtained through dynamics optimization ( α ≈ 13.92°, L ≈ 11.17 mm), and the centrifugal stress and static deformation of the rotor body are further reduced while increasing its fundamental frequency by about 7.15%, so that it can adapt to higher safety critical speed. The RNG k- ε turbulence physics model is applied to the numerical simulation of the airflow field in the optimal spinning channel, and a computational domain of single-phase steady fluid with nonstructural mesh is constructed by using ICEM CFD and FLUENT software. On this basis, the simulation result with excellent convergence of the flow field is obtained through the SIMPLE algorithm and pressure-velocity coupled solution. In addition, by virtue of the two-dimensional and three-dimensional flow field characteristic analysis for key fields (like the rotor wall, fiber pipeline, false twister, collecting groove, inlet and outlet), the airflow field state in the spinning channel (like the static pressure, dynamic pressure, velocity vector field, turbulence intensity and streamline trajectory) is confirmed, which will be conducive to gain a deep insight into the open-end spinning mechanism of the air-extraction rotor.

Boundary effects on ideal fluid forces and Kelvin's minimum energy theorem

The electrostatic force on a charge above a neutral conductor is generally attractive. Surprisingly, that force becomes repulsive in certain geometries (Levin & Johnson, Am. J. Phys., vol. 79, issue 8, 2011, pp. 843–849), a result that follows from an energy theorem in electrostatics. Based on the analogous minimum energy theorem of Kelvin (Camb. Dublin Math. J., vol. 4, 1849, pp. 107–112), valid in the theory of ideal fluids, we show corresponding effects on steady and unsteady fluid forces in the presence of boundaries. Two main results are presented regarding the unsteady force. First, the added mass is proven to always increase in the presence of boundaries. Second, in a model of a body approaching a boundary, where the unsteady force is typically repulsive (Lamb, Hydrodynamics, 1975, § 137, University Press), we present a geometry where the force can be attractive. As for the steady force, there is one main result: in a model of a Bernoulli suction gripper, for which the steady force is typically attractive, we show that the force becomes repulsive in some geometries. Both the unsteady and steady forces are shown to reverse sign when boundaries approximate flow streamlines, at energy minima predicted by Kelvin's theorem.

End-to-end wind turbine wake modelling with deep graph representation learning

Wind turbine wake modelling is of crucial importance to accurate resource assessment, to layout optimisation, and to the operational control of wind farms. This work proposes a surrogate model for the representation of wind turbine wakes based on a state-of-the-art graph representation learning method termed a graph neural network. The proposed end-to-end deep learning model operates directly on unstructured meshes and has been validated against high-fidelity data, demonstrating its ability to rapidly make accurate 3D flow field predictions for various inlet conditions and turbine yaw angles. The specific graph neural network model employed here is shown to generalise well to unseen data and is less sensitive to over-smoothing compared to common graph neural networks. A case study based upon a real world wind farm further demonstrates the capability of the proposed approach to predict farm scale power generation. Moreover, the proposed graph neural network framework is flexible and highly generic and as formulated here can be applied to any steady state computational fluid dynamics simulations on unstructured meshes.

A novel artificial neural network-based interface coupling approach for partitioned fluid–structure interaction problems

This paper presents a novel interface technique employing Artificial Neural Networks (ANN) for efficient data transfer between incompressible fluid and deformable solid domains in a partitioned fluid–structure interaction (FSI) framework. Governing differential equations (GDE) with potential flow assumptions are solved to obtain pressure values at computational nodes in the fluid domain. Pressure values are then used to train an ANN-based model to interpolate pressure loads for application at non-collocated nodes on the solid boundary. Both finite element method (FEM) and meshfree element free Galerkin (EFG) formulations are used to calculate the solid deformation. Proposed methodology is applied to solve a two-dimensional (2D) unidirectional flow problem, consisting of a flexible cantilever beam immersed in a laminar, steady, and inviscid fluid. Overwhelming mathematical intricacies of computational solvers are avoided for the sake of simplistic interface treatment, flux transfer and associated phenomena. Dedicated partitioned solvers are developed for both solid and fluid domains, which are individually benchmarked for established problems from the literature. The presented ANN-based interpolation scheme provides an alternative to higher-order polynomial algorithms at the interface boundary. The proposed scheme is simple to employ, computationally efficient, and offers competitive accuracy as well as stability.

UltraFLoads: A Simulation Suite and Framework for High-Fidelity Flight Loads

With the progress of high-performance computing, computationally expensive high-fidelity methods can be applied early in the design process of an aircraft. This enables Computational Fluid Dynamics (CFD) for the assesment of flight performance, handling qualities, flight loads due to manoeuver or gusts, and stability such as flutter. Those aeroealstic analyses require coupling of disciplines to adequately address the interplay of flexibility, aerodynamic forces and inertia forces. Previous work at the German Aerospace Center have demonstrated the proof of concept for those multidisciplinary analyses. Now, UltraFLoads is a simulation suite in the FlowSimulator ecosystem to offer standardized, multidisciplinary scenarios. UltraFLoads can be used as a tool, as a library and as a framework. This work describes the architecture, the integration layers, which scenarios are available and which equations are used. Three different applications are presented. The first case involves a steady fluid–structure-coupled simulation with geometrically nonlinear deformation. The second case compares the deformation of a simulated elastic, free-flying aircraft with actual flight test data. The last application demonstrates the flight dynamic capabilities with a bank to bank maneuver.

Improvement of mechanical energy using thermal efficiency of hybrid nanofluid on solar aircraft wings: an application of renewable, sustainable energy

ABSTRACT The modern world uses sun-based thermal radiation and nanotechnology to promote new technologies. In addition to solar thermal aircraft, photovoltaic cells, and sun-based hybrid nanofluids, solar energy is the primary source of heat derived from the absorption of sunlight. Researchers are currently investigating the application of nanotechnology to sun-based thermal radiation with the intent of enhancing the efficiency of aircraft flight. This study is focused on the research of heat transport via employing hybrid nanofluid on the interior of solar wings using a parabolic trough solar collector (PTSC) to enrich the investigations of the solar aircraft wing. In addition, the thermodynamics of entropy production for steady tangent hyperbolic fluid is examined for its energy balance and usefulness for significant physical influenced parameters. This study examines the viscoelastic properties of the thermal transfer process of two distinct kinds of nano solid particles, zirconium dioxide and copper (Cu), with non-Newtonian EG (ethylene glycol) as the base fluid. To achieve the model's aims, a novel solution, namely wavelets and the Chebyshev wavelets method (CWM), was employed to solve the velocity, energy equation, and entropy generation. .

Control of MHD Flow and Heat Transfer of a Micropolar Fluid through Porous Media in a Horizontal Channel

The problem considered in this paper is a steady micropolar fluid flow in porous media between two plates. This model can be used to describe the flow of some types of fluids with microstructures, such as human and animal blood, muddy water, colloidal fluids, lubricants and chemical suspensions. Fluid flow is a consequence of the constant pressure gradient along the flow, while two parallel plates are fixed and have different constant temperatures during the fluid flow. Perpendicular to the flow, an external magnetic field is applied. General equations of the problem are reduced to ordinary differential equations and solved in the closed form. Solutions for velocity, microrotation and temperature are used to explain the influence of the external magnetic field (Hartmann number), the characteristics of the micropolar fluid (coupling and spin gradient viscosity parameter) and the characteristics of the porous medium (porous parameter) using graphs. The results obtained in the paper show that the increase in the additional viscosity of micropolar fluids emphasizes the microrotation vector. Moreover, the analysis of the effect of the porosity parameter shows how the permeability of a porous medium can influence the fluid flow and heat transfer of a micropolar fluid. Finally, it is shown that the influence of the external magnetic field reduces the characteristics of micropolar fluids and tends to reduce the velocity field and make it uniform along the cross-section of the channel.

Computational analysis of conductive fluid flow with tangential components of magnetic flux density and electric field in metallic and non-metallic circular pipe

This paper has focused on the study of flow characteristics of a steady conductive fluid through a circular pipe in the presence of an applied transverse uniform magnetic field. A numerical simulation of the fluid flow was performed using a multi-physics computational tool. The radial velocity distribution due to the effect of the tangential component of induced magnetic flux density and electric fields at various axial positions is examined in metallic and non-metallic surfaces of the circular pipe. This simulation study helps to analyse the effect of drag force on the variation in axial velocity close to the metallic and non-metallic walls. The induced electric potential is directed along the normal to the Laplacian tangential surface of the pipe. In addition to that, sigmoidal-shaped field profiles are observed when the fluid flow crosses from the upstream to downstream of the magnet edge and vice versa along the axial length of the circular pipe. Simultaneously, it is observed that the average velocity of the fluid flow decreases for a laminar and increases for turbulent Reynolds number. Streamline plots pertinent flow variable such as flow velocity are presented for non-conducting and conducting walls.

Mathematical simulation of laminar micropolar fluid flow between two disks for two different geometries

In the present article, the physical behavior of an incompressible, laminar, and steady micropolar fluid flow among disks is analyzed for two different cases. Case I includes a rigid and a porous disk and case II includes two porous disks. By developing appropriate transformations, the governing equations are declined to a group of boundary value equations. The differential transformation scheme and the differential quadrature method are utilized to find the solutions to the problem. The outcomes are described to investigate the distribution of velocity and microrotation for various physical variables such as Reynolds number, microinertia density variable, the viscosity of vortex, and gradient viscosity of spin. By comparing the results obtained for the two geometries, it can be concluded that the microrotation and streamwise velocity in two porous disks (case II) are higher than those of case I. Furthermore, the results show that the microrotation reduces with increasing the micro-inertia density for both geometries.

Biomechanical Profiling in Real-Life Abdominal Aortic Aneurysms in Different Clinical Scenarios

The aim of this study was to demonstrate the biomechanical properties in different abdominal aortic aneurysm (AAA) presentations of real-life patients. We used the actual 3D geometry of the AAAs under analysis and a realistic, nonlinearly elastic biomechanical model. Three patients with different clinical scenarios (R: rupture, S: symptomatic, and A: asymptomatic) with infrarenal aortic aneurysms were studied. Factors affecting aneurysm behavior such as morphology, wall shear stress (WSS), pressure, and velocities were studied and analyzed using steady state computer fluid dynamics using SolidWorks (Dassault Systems SolidWorksCorp., Waltham, Massachusetts). When analyzing the WSS, Patient R and Patient A had a decrease in the pressure in the bottom-back region compared with the body of the aneurysm. In contrast, WSS values appeared to be the most uniform across the entire aneurysm in Patient S. Furthermore, Patient A had focal small surface regions with high WSS values. The overall WSS in the unruptured aneurysms (Patient S and Patient A) were a lot higher than in the ruptured 1 (Patient R). All 3 patients showed a pressure gradient, being high at the top and low at the bottom. All patients had pressure values 20 times smaller in the iliac arteries compared with the neck of the aneurysm. The overall maximum pressure was similar between Patient R and Patient A, higher than the maximum pressure of Patient S. Computed fluid dynamics was implemented in anatomically accurate models of AAAs in different clinical scenarios for obtaining a broader understanding of the biomechanical properties that determine the behavior of AAA. Further analysis and the inclusion of new metrics and technological tools are needed to accurately determine the key factors that will compromise the integrity of the patient's aneurysms anatomy.

On the Magnus effect of a rotating porous circular cylinder in uniform flow: A lattice Boltzmann study

In this paper, a multiple-relaxation-time–lattice Boltzmann method is used to simulate the steady fluid flow through and around a rotating porous circular cylinder in uniform flow. This study aims at investigating the effect of Darcy number (10−6≤Da≤10−2), velocity ratio (0≤VR≤2), and Reynolds number (Re = 20 and 40) on the Magnus lift as well as on the flow pattern and pressure coefficient inside and around the rotating porous cylinder. The results reveal that besides the enveloping and detached wakes reported in the literature for rotating solid cylinders, in this study, a new type of the wake called confined wake is observed within the rotating porous cylinders at high Darcy numbers and velocity ratios of less than one. It is seen that the Magnus lift increases almost linearly with the velocity ratio for Da≤10−3; however, through curve-fitting, the rate of increase is shown to decrease with Darcy number in a non-linear manner. For Darcy numbers higher than 10−3, the Magnus lift varies non-linearly with both the velocity ratio and Darcy number in such a way that, interestingly, for Re=40 and very high Darcy numbers of 7.5×10−3 and 10−2, the Magnus lift becomes negative showing a behavior called the inverse Magnus effect.

Development of 3D transient neutronics and thermal-hydraulics coupling procedure and its application to a fuel pin analysis

This paper develops a three-dimensional fine-mesh coupled neutronics and thermal-hydraulics platform based on the open-source software OpenFOAM. For the neutronics, a three-dimensional multi-group multi-region neutron diffusion solver is developed for steady and transient problems with macroscopic cross-sections generated by the Monte Carlo code OpenMC. By modeling and calculating three typic neutronic benchmark problems, the results are compared with that of other programs to verify the correctness of this solver to solve neutron diffusion equations. The thermal-hydraulics is solved by the built-in solid-fluid conjugated heat transfer solver for steady or transient fluid flow and solid heat conduction between different regions. The unified solution of a coupled neutronic and thermal-hydraulic problem is implemented in the solver with the same time step size and the same set of meshes. The feasibility and rationality of this coupling procedure is verified through the simulation the 5×5 PWR assembly. Furthermore, the operator-splitting semi-implicit (OSSI) method and the fixed-point implicit (FPI) method have been applied to the coupling procedure. The performance of the above two neutronic and thermal-hydraulic coupling algorithms is evaluated by simulating the coolant inlet temperature decrease accident in a single fuel pin model of the pressurized water reactor. The numerical results indicate that the FPI coupling method outperforms the OSSI coupling method due to its accuracy and stability.

From the Nash–Kuiper theorem of isometric embeddings to the Euler equations for steady fluid motions: Analogues, examples, and extensions

Direct linkages between regular or irregular isometric embeddings of surfaces and steady compressible or incompressible fluid dynamics are investigated in this paper. For a surface (M, g) isometrically embedded in R3, we construct a mapping that sends the second fundamental form of the embedding to the density, velocity, and pressure of steady fluid flows on (M, g). From a Partial Differential Equations perspective, this mapping sends solutions to the Gauss–Codazzi equations to the steady Euler equations. Several families of special solutions of physical or geometrical significance are studied in detail, including the Chaplygin gas on standard and flat tori as well as the irregular isometric embeddings of the flat torus. We also discuss tentative extensions to multiple dimensions.

Dimensional investigation of solar chimney power plant based on numerical and experimental results

• Construction of prototype solar chimney and recording air flow temperature and velocity data under different solar radiation. • 3D numerical simulation of the base case using FLUENT software and validation of the results with the experimental results obtained in this study and also validation with other researcher's numerical and experimental results. • Investigation of the fluid behavior pattern inside the solar chimney and system performance based on the simulation results under different geometric parameters. In this study, a pilot solar chimney power plant (SCPP) with a chimney height of 4 m and a collector diameter of 5 m was constructed. Main purpose of this research is identification and optimization of the system based on regional climatic experimental data which recorded from constructed solar chimney with new dimensions to utilize in our future studies. So that future studies can be conducted based on a suitable platform. Performance evaluation of solar chimney was simulated under different geometric configurations through a 3D axisymmetric incompressible steady computational fluid dynamics solver by applying k - ε turbulence model. For a better performance comparison of the SCPP between different geometries, air velocity and system output power were calculated for all states. The results showed that a higher collector radius and chimney radius increased the ​​air outflow velocity in the collector, whereas a higher collector height had a negative effect. According to the results, configurations with collector height of 5 cm have the highest velocity values compared to the others and the maximum power value of 1.74 W can be achieved for the collector inlet height of 15 cm and the chimney radius of 0.4 m.

Partial regularity for steady double phase fluids

<abstract><p>We study partial Hölder regularity for nonlinear elliptic systems in divergence form with double-phase growth, modeling double-phase non-Newtonian fluids in the stationary case.</p></abstract>

Nano- and micro-polar magnetohydrodynamic fluid-flow and heat transfer in inclined channel

Magnetohydrodynamic (MHD) fluid flows attract a lot of attention in the extrusion of polymers, in the theory of nanofluids, as well as in the consideration of biological fluids. The considered problem in the paper is the flow and heat transfer of nano and micropolar fluid in inclined channel. Fluid flow is steady, while nano and micropolar fluids are incompressible, immiscible, and electrically conductive. The upper and lower channel plates are electrically insulated and maintained at constant and different temperatures. External applied magnetic field is perpendicular to the fluid flow and considered problem is in induction-less approximation. The equations of the considered problem are reduced to ordinary differential equations, which are analytically solved in closed form. The influence of characteristics parameters of nano and micropolar fluids on velocity, micro-rotation and temperature fields are graphically shown and discussed. The general conclusions given through the analysis of graphs can be used for better understanding of the flow and heat transfer of nano and micropolar fluid, which have a great practical application. Fluids with nanoparticles innovated the modern era, due to their comprehensive applications in nanotechnology and manufacturing processes, while the theory of micropolar fluids explains the flow of biological fluids and various types of liquid metals and crystals.