Wall Force Research Articles

Undular surges interaction with a vertical wall

The interaction of nonbreaking and breaking undular surges with a vertical wall is experimentally investigated. The results for nonbreaking undular surges demonstrate that the maximum run-ups agree quantitatively with the predictions of solitary wave theory. During the run-up of a nonbreaking undular surge, the maximum dynamic pressure on a vertical wall occurs at an elevation in the vicinity of the quiescent water level. Both the maximum dynamic pressure and maximum wall force can be accurately estimated from the wave amplitude of the incident surge. By contrast, the breaking surge interactions result in significant amplifications of maximum run-ups and tend to yield extremely high impact pressures at elevations significantly above the still water level. The experimental results indicate the occurrence of extreme impact events for normalized maximum pressures exceeding 1.13. Based on these experimental results, a numerical method is employed to discuss the analogy between a nonbreaking undular surge and a solitary wave. In general, the present results show that the leading front of a nonbreaking undular surge during its initial wave evolution can be satisfactorily described using the solitary wave equation.

Effect of time-of-day on freestyle flip turn performance: influence on 50 m event

ABSTRACT The aim of this study is to examine the daytime effects on flip turn performance [i.e., 3 m round trip time (3mRTT) as measure of turning performance] as well as global performance during a 50 m freestyle at maximal speed. Twelve college swimmers performed 3 × 50 m freestyle at maximum speed with a flip turn and glide in a 25 m pool in two experimental trials, one in the morning (08:00 h) and one in the evening (18:00 h). Kinematic and dynamic parameters of flip turn performance are analyzed using one underwater camera and a force platform recording wall force peak and time contact. Results showed that oral temperature is significantly higher (p < 0.001) in the evening than in the morning. Also, this study reported that daily variations have been observed for both, changes in swim performance and changes in (3mRTT). Thus, kinematic and dynamic flip turn variables associated with an improvement of freestyle swim performance. It is concluded that maximal swimming trials are performed better in the evening than in the morning, and that this might be linked to variations in oral temperature; also, might be explained by better flip turn performance at this time.

Azadirachtin-A a bioactive compound from Azadiracta indica is a potential inhibitor of SARS-CoV-2 main protease

Despite the growing scientific interest in finding effective treatment, SARS-CoV-2 virus remains a global major health burden and public health emergency. SARS-CoV main protease (Mpro) also known as chymotrypsin-like protease (3CLpro) is an important protein identified to be vital for SARS-CoV-2 survival. However, to date, there are no clinically approved drugs or antibodies specific for SARS-CoV-2. In the present study, we evaluated the interaction of 3CLpro with azadirachtin-A a bioactive compound from Azadiracta indica using in silico molecular docking study. Our results revealed that Azadiractin A docked well into the binding cavity of 3CLproSARS-CoV-2 with binding affinities ranges between -6.3 and -5.20 kcal/mol, and Pkd of 5.82~6.10 for the ten best binding modes. Azadiractin interacted with the active site of 3CLpro-SARS-CoV-2 by 2 conventional hydrogen bonding to HIS163 and GLU166, C-H interactions with HIS127, and alkyl interaction with PRO168 of the 3CLpro-SARS-CoV-2. We also found that the Azadiractin-A_3CLpro-SARS-CoV-2 complex is stabilized by various Vander wall forces with ASN142, LEU141, PHE140, MET165, GLN189, LEU167, THR190, and ALA191. In conclusion, our results suggested that Azadirachtin-A could be a potential inhibitor of SARS-CoV-2 main protease, thus worthy of further preclinical study.

Experimental analysis of wheat-wall friction and grain flow in a steel silo with corrugated walls

Frictional behaviour of wheat on corrugated steel walls, pressure distribution, and grain flow were investigated using a silo model with a square cross section. Corrugated steel sheets were attached to both side walls of the model silo, while clear polymethyl methacrylate was used for the front and rear walls to allow observation of the flow. In addition, a truncated steel pyramid was used for the hopper and a square outlet with sides varying from 0.02 m to 0.06 m. A test panel was placed at one of the side walls in the place of a cut off fragment of the wall to measure lateral and frictional wall forces. The tests were conducted using winter wheat, and two filling methods (central and distributed) were considered to analyse their possible influence on bulk density or shear behaviour during silo discharge. It was found for the distributed filling that the grain-wall friction coefficient during discharge was nearly 20% larger than that for the central filling. This coefficient was found to increase slightly with the increasing size of the outlet, a trend that was not observed for the central filling. The experimentally determined pressures and coefficient of wheat-wall friction were compared with the recommendations of Eurocode standard EN 1991-4. Differences between the experimental and theoretical results demonstrate that the formulae proposed by the Eurocode do not take into account some important issues associated with friction between the grain and the corrugated silo wall. • A silo with corrugated steel walls was constructed. • A test panel was placed at the side wall to measure lateral and vertical forces. • A side length of an square outlet in truncated pyramid hopper was varied. • No effect of the filling method on the mass flow rate of material was found. • Larger wheat-wall friction coefficient for distributed filling was obtained.

3D simulations of vertical displacement events in tokamaks: A benchmark of M3D-C1, NIMROD, and JOREK

In recent years, the nonlinear 3D magnetohydrodynamic codes JOREK, M3D-C1, and NIMROD developed the capability of modeling realistic 3D vertical displacement events (VDEs) including resistive walls. In this paper, a comprehensive 3D VDE benchmark is presented between these state-of-the-art codes. The simulated case is based on an experimental NSTX plasma but with a simplified rectangular wall. There are differences between the physics models and numerical methods, and the VDE evolution leads to sensitivities on the initial conditions that cannot be avoided as can be done in edge localized modes (ELM) and sawtooth simulations (due to the non-cyclical nature of VDEs). Nonetheless, the comparison serves to quantify the level of agreement in the relevant quantities used to characterize disruptions, such as the 3D wall forces and energy decay. The results bring confidence regarding the use of the mentioned codes for disruption studies, and they distinguish aspects that are specific to the models used (e.g., reduced vs full MHD models). The simulations show important 3D features for a NSTX plasma, such as the self-consistent evolution of the halo current and the origin of the wall forces. In contrast to other reduced MHD models based on an ordering in the aspect ratio, the ansatz-based JOREK reduced MHD model allows capturing many aspects of the 3D dynamics even in the spherical tokamak limit considered here.

Analisis dan Desain Struktur Atas Hotel 10 Lantai di Kabupaten Bogor terhadap Beban Gempa

The type of soil at the location of the hotel building is a type of medium land (D). The applications used in this study are ETABS V16.1 and AutoCAD. Based on the PUSKIM website, the Ss and S1 Bogor City were 0.881 and 0.356, respectively. Based on the results of the analysis of the application ETABS V16.1 obtained fewer reinforcement design results than the existing reinforcement. The maximum nominal moment of the beam is 508.3 kNm while the ultimate moment is 498.4 kNm. The maximum nominal shear force of the beam is 565.9 kN while the ultimate shear force is 538.4 kN. The maximum nominal moment of the column is 1488.5 kNm while the maximum ultimate moment is 1478 kNm. The maximum nominal axial force of the column is 6291 kN while the maximum ultimate axial force is 6287 kN. The maximum nominal bending moment of the floor plate is 41.3 kNm while the maximum ultimate moment is 39.9 kNm. The maximum nominal shear force of the floor plate is 234.7 kN while the maximum ultimate shear force is 228.9 kN. The nominal shear force of shear wall is 8238.5 kN while the ultimate shear force is 8194.7 kN. Based on the internal forces, the building that has been built is in accordance with the plan so that it is safe to withstand earthquake loads.&#x0D;

Design optimization for protective shell of hydrogen cylinder for vehicle based on NPR structure

Aiming at reducing the energy absorption of the hydrogen cylinder for fuel cell vehicles in collision, which may lead to fierce explosion, this paper introduces an energy-absorbing protective shell combining with negative Poisson’s ratio (NPR) structure to the hydrogen cylinder. It adopts three honeycomb structures of the same mass and three kinds of aluminum alloy to determine the optimal structure and material scheme of the protective shell. Besides, sensitivity analysis is selected to screen the design parameters of the optimal structure scheme. Based on this, the overall mass of the designed protective shell, the specific energy absorption of NPR structure, the maximum impact force of rigid wall, and the maximum stress of the liner are taken to establish the optimization mathematical model. Furthermore, adaptive mutation genetic algorithm (AMGA), non-dominated sorting genetic algorithm-ii (NSGA-II), and adaptive simulated annealing algorithm (ASA) are exerted as the optimization algorithms separately to conduct optimization design and a comparison is made between the optimization results. The results show that the optimized energy-absorbing protective shell has better crashworthiness and energy absorption effect, which can effectively improve the collision safety of the hydrogen cylinder. It provides a new idea for the protection design of hydrogen storage system in fuel cells in the future.

Wave Trapping Efficiency of a Flexible Membrane Near a Partially Reflecting Seawall

Abstract The gravity wave interaction with a flexible membrane placed at a finite distance from the partially reflecting seawall is analyzed under the framework of linear water wave theory using the multi-domain boundary element method (BEM). The flow through a flexible membrane is assumed to follow Darcy’s law in addition to membrane displacements. As a viable alternative to the existing wave dampers, the flexible membrane is examined for the effective dampening of incident waves. The correctness of the numerical results is affirmed with the known results available in the literature. The effect of membrane tension, submergence depth, membrane width, porosity, angle of inclination, and confined chamber spacing on hydrodynamic coefficients is discussed as a function of dimensionless wavenumber. The partially reflecting harbor wall diminishes the wave reflection coefficient in the long-wave regime. The increase in the flexible membrane width does not necessarily ensure the ideal wave capturing performance. A shift in the peak of the maximum deflection is observed with the increase of membrane width while there is a shift in peak outward for the increase in the submergence depth. Moreover, the maximum deflection is found to decrease with the increase in porosity, and it is 62% reduction for membrane porosity b = 1 due to the significant wave damping. The wave run-up and the wall force coefficients are found to be minimum when the relative plate width is B/h = 1. The present study is expected to be useful for the design of cost-effective wave attenuating systems.

Probing the prediction of effective properties for composite materials

This article presents different micromechanical modelling techniques based on analytical and numerical approaches to determine the effective elastic and piezoelectric (piezoelastic) properties of graphene-based composite materials. Different types, orientations and shapes as well as different geometrical parameters of fiber reinforcement are considered for estimating the effective properties. The effective properties of composite are predicted with and without considering the strong covalent bond which provides interaction and in-plane stability of 2Dcrystalline graphene or strong van der Wall forces formed between graphene layers and the matrix. It is revealed that the axial, transverse and shear effective piezoelastic properties of graphene reinforced piezoelectric composite (GRPC) are significantly enriched due to the incorporation of graphene into the epoxy matrix. The importance of incorporating graphene as nanofillers/interphase into the conventional epoxy matrix to form an advanced composite and its effective properties are illustrated while these results show excellent agreement with previously reported experimental estimates. These results reveal that due to incorporation of graphene nanofillers, there is a significant enhancement in effective properties of composite. The results would also help to recognize the most important material properties with respect to different shapes and orientation of reinforcements which influences the performance of system significantly. To confirm safety, robustness and sustainability of the structure, it is the most prior requirement to determine the effective properties of composites considering different parameters for the different static and structural analyses.

Analysis of the Influence of Short-Time Load on Deep Foundation Pit

The foundation pit of shield working well needs to meet the requirements of shield assembly, starting, and hoisting. The short-time load at the edge of the pit is frequent and the construction conditions are more complicated. This paper takes the foundation pit of a certain project in Jinan as the research background. Based on field measured data, based on theoretical analysis. The force and deformation laws of the underground diaphragm wall + internal bracing structure under short-term load are studied, and some conclusions can be used to guide the design and construction.

Investigations of the hot granular material effect on steel silo

When the hot granular material is placed in a steel silo, there will be significant thermal effects on bending moment, shear force and stress of the silo wall. But there is no feasible method to identify the stress and deformation of the silo with hot granular material. To fill this gap, this paper proposes an analytical method based on the cylindrical shell theory. A case study is performed to demonstrate the accuracy and feasibility of the analytical method. The results show that the proposed method produces satisfactory results when comparing with the finite element method. Besides, it can be seen from the analysis that large radial displacement occurs in the middle height of the silo wall when the hot granular material is placed in. Afterwards, the parametric studies are conducted to investigate the structural behaviors of the silo under different conditions that produces useful information for considering thermal effects in silo design. The research findings show that the length of the transition zone, the vertical temperature differential and the ratio of radius to thickness significantly influence the thermal stresses, which should be paid attention to in practical engineering design.

A Comparative Study of Closure Relations for CFD Modelling of Bubbly Flow in a Vertical Pipe

Commercial code CFX was used to examine the performance of a two-fluid model to predict the details of upward isothermal bubbly flow of air and water in a vertical pipe. The model equations are volume-averaged Navier-Stokes equations that require closure models for interfacial forces and bubble-induced turbulence effects. Two-equation SST and k-epsilon RANS turbulence models were also used. A parametric study of closure models included both standard options in CFX and previously published novel closure models that were implemented with user-defined functions. The CFD simulations were compared with two cases from the MTLoop experiments by Lucas et al. at the Helmholtz-Zentrum Dresden Rossendorf: one with wall-peak void fraction profile (MT039), and another with a core-peak void fraction profile (MT118). The effect of changing the drag force closures was not significant for the set examined. Poor predictions were found when the lift force and wall lubrication models were incompatible in magnitude. There was no significant effect of changing the liquid phase turbulence model. Changing the bubble-induced turbulence models, however, had a significant impact on the radial void fraction profile. The novel wall force from Lubchenko et al. at the Massachusetts Institute of Technology significantly improved the prediction of the near wall void fraction in the wall peak profile.

Field Study on Deformation and Stress Characteristics of Large Open Caisson during Excavation in Deep Marine Soft Clay

Oujiang River North Estuary Bridge in Wenzhou is the world’s first double‐deck suspension bridge under construction with three‐tower and four‐span. It is the first time to build large open caisson foundation in the deep marine soft clay in estuary with strong tide, extending the application scope of caisson. To study the deformation and stress characteristics of large open caisson during excavation and ensure the safety of anchorage excavation, a large number of sensors are arranged in the caisson. By analyzing the change of tip resistance, lateral soil pressure, and posture parameters during caisson excavation, the stress characteristics and deformation of caisson are described. The result shows the following. (1) Because of the thixotropy of soft clay, the reaction force of partition wall in deep soft soil area of caisson is similar to that of blade foot, and the reaction force of blade foot can be effectively reduced through the layering construction of caisson. (2) The height of caisson construction and the sand‐bearing stratum will obviously affect the plane torsion angle of caisson. When the caisson enters the sand‐bearing stratum, the lateral soil pressure increases significantly, which leads to the increase of the plane torsion angle. (3) The inclination and central deviation of caisson are sensitive to the caisson construction and stratum property. It can be found that the lateral soil pressure, plane torsion angle, inclination, and central deviation of caisson are sensitive to stratum property, and inhomogeneity of stratum easily leads to inclination of caisson. Based on the field monitoring data, the stress characteristics and geometric posture of caisson during sinking are studied, which provide technical guidance for scheme design and subsidence prediction analysis of caisson in deep marine soft clay. It can provide a good opportunity to study the behaviors of large caisson foundation constructed in deep marine soft clay and has great significance and reference value for construction optimization of anchorage structure.

Comparison of Totally Extraperitoneal versus Transabdominal Preperitoneal repair of inguinal hernias

Introduction: Laparoscopic inguinal hernia repair is a tension-free mesh repair that is based on pre-peritoneal approach of repair. It provides mechanical advantage to the surgeon, by being able to place a large piece of mesh and by using the natural force of the abdominal wall to disperse the intra-abdominal pressure over a large area to support the mesh. This retrospective study is aimed to study the demography of inguinal hernia and to compare operating time, complications and postoperative pain between patients undergoing Total Extrapritoneal (TEP) or Transabdominal Preperitoneal (TAPP) repair.Methods: A retrospective comparative study was conducted in patients with inguinal hernia who underwent laparoscopic repair by either TEP or TAPP, between April 2019 to July 2020 at Nobel Medical Collage Teaching Hospital, Biratnagar, Morang. Age, sex, type of hernia, duration of operation, post-operative complications, severity of pain and duration hospital stay were analyzed between two groups of patients undergoingsurgery by either TEP or TAPP.Results: One hundred and five patients underwent either TEP or TAPP during study period. There were 96 males and 9 females. There were 50 patients with right, 40 with left and 6 patients with bilateral inguinal hernia. Four patients had left sided irreducible inguinal hernia, 2 patients had bilateral recurrent inguinal hernia, 2 patients had right sided recurrent inguinal hernia and 1 patient had left sided recurrent inguinal hernia.There was significant difference in duration of operation (TEP 64.43min) / (TAPP 84.46min), p&lt;0. 001. Total duration of hospital stay and postoperative pain were not significant between patients operated with TEPor TAPP. Accidental pneumoperitoneum was noticed in 8 cases, 10 cases of subcutaneous emphysema, 5 cases of seroma and 1 case of scrotal hematoma in TEP group. In TAPP group scrotal hematoma occurred in 4 cases and seroma in 5 cases which was not significantly different from TEP group.Conclusion: TAPP had significantly longer operating time as compared to TEP. However, there was no significant difference in post-operative pain and hospital stay in both group.

STORM-DRIVEN WAVE IMPACT LOADS AND SCOUR AT A BEACH SEAWALL

The Grande-Motte port and seafront development project on the French Mediterranean coastline entailed evaluating wave impact loads (pressures and forces) on the new beach seawall and comparing the resulting scour potential at the base of the existing and new seawall. A physical model was built at ARTELIA's hydraulics laboratory in Grenoble (France) to provide insight into: wave and setup at the beach, the evolution of scour over time at the front of the wall, quasi-static and impulsive wave force intensity and distribution on the wall, and water and sand overtopping discharges over the wall. Light-weight sediment physical model and pressure and force measurements were performed with scale 1:18. The paper will discuss the pros and cons of a physical model versus numerical/ empirical modelsRecorded Presentation from the vICCE (YouTube Link): https://youtu.be/AeW3SPwDtVg

Coupling of turbulence wall models and immersed boundaries on Cartesian grids

An improved coupling of immersed boundary method and turbulence wall models on Cartesian grids is proposed, for producing smooth wall surface pressure and skin friction at high Reynolds numbers. Spurious oscillations are frequently observed on these quantities with most immersed boundary wall modeling methods, especially for the skin friction which is found to be very sensitive to the solid surface's position and orientation against the Cartesian grids. The problem originates from the irregularity of the wall distance on the stair-step grid boundaries where the immersed boundary conditions are applied. To reduce this directional error, several modifications are presented to enhance the near wall solution. First, the commonly used interpolation for the flow velocity is replaced by one for the friction velocity, which has much less variation near wall. The concept of using a fictitious point to retrieve flow fields in the wall normal direction is abandoned and the interpolation is performed in the wall parallel plane with existing fluid points. Secondly, the velocity gradients at the approximated boundary are computed with advanced schemes and the normal gradient of the tangential velocity is reconstructed from the wall laws. To further protect the near wall solution, the normal velocity gradient and the working viscosity from the Spalart-Allmaras turbulence model are enforced by their theoretical solutions in the interior fluid close to the wall. Additionally, various post-processing algorithms for reconstructing wall surface quantities and force integrations are investigated. Other related factors are also discussed for their effects on the results. The validity of present method has been demonstrated through numerical benchmark tests on a flat plate at zero pressure gradient, both aligned and inclined with respect to the grid, as well as aerodynamic cases of NACA 23012 airfoil and NASA trap wing.

Ballistic propagation of density correlations and excess wall forces in quenched granular media

We investigate a granular gas in a shaken quasi-two-dimensional box in molecular dynamics computer simulations. After a sudden change (quench) of the shaking amplitude, transient density correlations are observed orders of magnitude beyond the steady-state correlation length scale. Propagation of the correlations is ballistic, in contrast to recently investigated quenches of Brownian particles that show diffusive propagation [Rohwer etal., Phys. Rev. Lett. 118, 015702 (2017)PRLTAO0031-900710.1103/PhysRevLett.118.015702, Rohwer etal., Phys. Rev. E 97, 032125 (2018)2470-004510.1103/PhysRevE.97.032125]. At sufficiently strong cooling of the fluid the effect is overlaid by clustering instability of the homogeneous cooling state with different scaling behavior. We are able to identify different quench regimes. In each regime correlations exhibit remarkably universal position dependence. In simulations performed with side walls we find confinement effects for temperature and pressure in steady-state simulations and an additional transient wall pressure contribution when changing the shaking amplitude. The transient contribution is ascribed to enhanced relaxation of the fluid in the presence of walls. From incompatible scaling behavior we conclude that the observed effects with and without side walls constitute distinct phenomena.

Force of Wall

Rafael Cauduro’s mural The Seven Crimes of Justice, situated in the Supreme Court of Mexico, speaks to the old problem of the relationship between art, politics and the State. In Mexico City, the birthplace of modern muralism, Rafael Cauduro confronts its ambivalent legacy and offers up new solutions. And at the same time, at the very heart of the legal system, Cauduro presents a critique of law and justice almost unprecedented in its uncompromising determination to lay bare the brutality of contemporary legal phenomena, not just in Mexico but around the world. This essay examines how Cauduro’s aesthetic choices address the history of modern muralism, and how his thematic choices address the history of modern law. But above all, how do these two modes of representation, the visual and the legal, actually relate to one another? Murals and law have something in common—a belief in the force of walls. The Seven Crimes of Justice binds this common thematic together in a remarkable work that has to date attracted little critical attention. This essay gives it the attention it deserves, focusing on questions of time and memory, and of the relationship between the force of law and the force of art.

Unusually located proximal middle cerebral artery saccular aneurysm

Middle cerebral aneurysms constitute almost one-third of all anterior circulation aneurysms. Most of the saccular aneurysms originate from the arterial branching sites, but origins other than at the branching site are extremely rare. In this article, we are describing a unique M1 segment middle cerebral artery aneurysm which is not related with any branching site. Our literature search suggests that atherosclerotic changes in the arterial wall and local hemodynamic forces play an important role in the development of these types of aneurysm. Surgical management is not so unique in this type of aneurysm, but due to atherosclerotic parent arterial wall and thin-walled aneurysm sac, a neurosurgeon should be more cautious.

Analysis and numerical modeling of subcooled boiling in energy systems in vertical porous channel

Boiling phenomena are interested in many fields of engineering such as piping and cooling electronic systems. Usually, the phase change through the heat transfer process is avoided as it makes the fluid flow unstable and complex. In the current study, the effect of using porous media in the channel to control the thermo-hydraulic characteristics of the system is studied. To do this aim a steady-state one-dimensional system of equations is solved by numerical method. The gas and liquid Navier–Stokes equations coupled with energy equations are solved simultaneously. The developed method validated with a well-known benchmark problem and the comparison shows a good agreement. The results show that Sauter bubble diameter, forces on the cross-sectional area of fluid, Froude number, fluid wall forces, velocity of mixture, Reynolds number of vapor, fluid velocity, square root of Froude number divided by Weber number, base volume fraction, vapor volume portion, maximum vapor volume portion, critical vapor volume fraction decrease by an increase in Darcy forces, while mean root square of the applied force over the cross section of fluid and heat transported by thermal radiation increased by an increase in Darcy friction up to 1000. The porous media parameters have negligible effects on Eotvos number, speed of sound, liquid Reynolds number, bubble departure frequency, convection heat transfer coefficient, and critical pipe diameter.