Effects Of Coriolis Forces Research Articles

Investigation on Free Vibration of Rotating Cylindrical Shells with Variable Thickness

In order to improve the performance and efficiency of the rotating cylindrical shell (RCS), one of the effective ways reduces the mass of the RCS. The scientific and effective method is to design the variable thickness of RCS (VTRCS) along the axial direction in response to this demand. Then, the vibration traveling wave characteristics of VTRCS are investigated by Chebyshev–Ritz method. The displacement field of the cylindrical shell is expanded in the form of the product of the Chebyshev polynomial and the boundary function. The kinetic and potential energies of the VTRCS are calculated based on the Sanders shell theory considering the effects of Coriolis forces and centrifugal forces. Also, the frequency equation of the VTRCS is obtained according to the Ritz method. The accuracy of the modeling method is verified by comparing the present results with literature that had done, and the convergence of the calculated results is studied. Finally, the free-vibration traveling wave characteristics of the VTRCS in different thickness variations are compared, and the parameters such as the rotational speed, thickness variation parameters, and aspect ratio on the free-vibration traveling wave characteristics of the VTRCS are discussed. The influence of thickness variation on the vibration characteristics is analyzed, which has significance for the lightweight design for VTRCS.

Free-vibration analysis of rim-driven rotating composite plate using NURBS-based isogeometric approach and HSDT

This paper presents free-vibration analysis of a rim-driven rotating composite plate. Based on higher-order shear deformation theory (HSDT) and the isogeometric approach (IGA), the formulations are developed. The effects of Coriolis and centrifugal forces due to rotation are considered. The present formulation results are compared and validated with the existing results for the hub-driven rotating plate, non-rotating plate, etc. A parametric study is conducted to investigate effect of the lamination sequence, pitch angle, material anisotropy, thickness ratio, and aspect ratio on natural frequency, critical buckling speed, and resonance speed. Natural frequency crossing and mode shape interchange are observed.

Numerical investigation of neutral atmospheric boundary layer flows over flat terrain and three-dimensional hills considering the effects of Coriolis force

The characteristics of neutral atmospheric boundary layer (ABL) flows can be strongly affected by terrain and earth rotation-induced Coriolis force. The purpose of this study is to ascertain the effects of Coriolis force on neutral ABL flows over flat terrain and isolated three-dimensional hills. Based on large-eddy simulations (LES), a new formula for the maximum turbulence length scale lmax in the limited-length-scale (LLS) k-ε model is proposed to reproduce neutral ABL flows over flat terrain with different exposure conditions. It is demonstrated that lmax can be reasonably expressed as a function of the geostrophic wind speed Ug, the Coriolis parameter fc and the roughness length z0. The effects of Coriolis force on atmospheric flows over single isolated hills are subsequently elucidated from the perspective of flow patterns and turbulent statistics. The wake trajectory deflection and asymmetric vortex structures are identified on the lee side of hills owing to the wind veer. Additionally, lateral wind shear associated with the Coriolis force contributes to a faster wake recovery and larger turbulence fluctuations downstream of steep hills. Moreover, the speed-up factor at the hilltop is significantly enhanced with increasing hill slopes and height ratios, while it is not sensitive to the Coriolis effects.

Influences of space perturbations on robotic assembly process of ultra-large structures

The space assembly of two flexible beams by a dual-arm space robot is a typical assembly scenario to construct ultra-large space structure. Yet, previous studies mainly focused on the assembly of small structures, neglecting the influences of space perturbations. Two models are developed in this research to investigate the effects of space perturbations on the space assembly process of ultra-large space structures. Firstly, a theoretical modelling method is proposed based on quasi-static hypothesis and linear structural mechanics. The theoretical model can be utilized for analytically estimating the transverse and axial distributed forces of the flexible beams, structural vibrations, and the control moments of the space robot. An orbit–attitude–structure coupled simulation model is then established to validate the theoretical model and study the dynamic behaviours more accurately, using absolute nodal coordinate formulation and natural coordinate formulation. Finally, the effects of the attitude angle, orbital radius, and lengths of beams on the dynamic responses during assembly are investigated. Theoretical and simulation results show that the control moments and structural vibration amplitude increase dramatically with the length of the beams. The effects of Coriolis force and gravity gradient must be considered for ultra-large space structures during assembly, otherwise the control moments and structural vibrations would be substantially underestimated. The results are instructive to the assembly strategy design as well as modular component design of ultra-large space structures.

Effect of Coriolis Force on Modified Eyring Powell Fluid flow

Recently, it has been shown that under certain conditions, the Eyring-Powell fluid model can exhibit shearthickening properties without losing the known Newtonian or shear-thinning properties. The Eyring-Powell and Modified Eyring-Powell fluids have shown great potential in enhancing armour production and reducing the cost of maintenance for bullet proof vests. The Coriolis force, on the other hand, explains natural phenomena such as the direction of cyclones and the true direction of sun rays on earth. In this paper, the shear-thinning properties of the Eyring-Powell fluid is explored under the action of Coriolis force. The flow is modelled as a system of PDEs which are transformed into a system of ODEs by means of similarity variables. A numerical solution of the equations are sought using the Runge-Kutta scheme alongside the Shooting technique. The effects of the Eyring-Powell fluid parameter and Coriolis force are explored on the flow velocity and flow temperature and the results are illustrated as graphs. The outcomes show that temperature increases with increasing Coriolis force but flow velocity decreases as Coriolis force increases.

Three-dimensional vibration analysis of rotating pre-twisted variable thickness blades composed of spanwise graded functional materials

In this study, the isogeometric method is used to obtain a three-dimensional (3-D) solution for the vibration of rotating pre-twisted blades composed of spanwise functionally graded materials (SFGM). The material properties are assumed to change continuously in the spanwise direction according to a mixture rule. Nonuniform rational B–splines (NURBS) are used to describe the unknown displacement and geometry of the rotating blades, whose thickness linearly tapers along the spanwise direction. A typical isogeometric element for a rotating pre-twisted variable thickness SFGM blade is introduced to prevent transformations among multiple coordinate systems. This model considers centrifugal stiffening, centrifugal softening, and Coriolis force effects. Several cases are studied, including rotating rectangular plates, partial cylindrical shells and conical shells with different material properties and geometric parameters. The predicted vibration behaviors are verified by comparisons with results from the literature and commercial finite element software. The comparisons show that the current model has good accuracy. Finally, the influence of material properties, rotating speeds, installation angles, pre-twist angles, and variable thicknesses on the vibrational characteristics of rotating pre-twisted SFGM blades are examined.

Dynamic analysis of a rigid-flexible inflatable space structure coupled with control moment gyroscopes

The vibration generated by the inflatable structure after deployment has a great impact on the performance of the payloads. In this paper, the influence of the control moment gyroscopes (CMGs) on the dynamic responses and characteristics of an inflatable space structure is studied, based on the flexible multibody dynamics in a combination of the absolute nodal coordinate formulation (ANCF) and the natural coordinate formulation (NCF). Firstly, the ANCF and NCF are used to accurately describe the large deformations and large overall motions of flexible inflatable tubes and rigid satellites, respectively. Then, instead of modeling gyroscopic flexible bodies, this paper pioneers a rigid body dynamic model of the CMG in detail by using the NCF modeling scheme, which can be attached to and coupled with any flexible bodies without any assumptions. Then, the orbital dynamic equations of the inflatable space structure coupled with distributed CMGs are obtained by considering the effects of Coriolis force, centrifugal force, and gravity gradient through coordinate transformation. The dynamic characteristics of the inflatable space structure are also analyzed by deriving the eigenvalue problem of a flexible multibody system. Finally, the accuracy of the CMG dynamic model is verified via a classic heavy top example. Several numerical examples are presented to study the influence of the magnitudes and directions of the rotor angular momentum of the CMGs on the dynamic responses and characteristics of the inflatable space structure.

Semi-analytical modeling and experimental verification of a flexible varying section disk–blades system with elastic supports

A semi-analytical model of a flexible varying section disk–blades (FVSDBs) system with elastic supports is proposed, where the spin softening, centrifugal stiffening, and Coriolis force effects of the system are considered. Timoshenko beams with a stagger angle are used to simulate blades, and a varying section wheel based on plate theory is used to construct the disk. Hamilton’s principle and Galerkin method are utilized to derive the differential governing equations of the FVSDBs system. The proposed semi-analytical model accounts for the lateral vibration of the disk, and the longitudinal and lateral vibration of the blades. Besides, the validity of the proposed model has been verified by comparing the natural frequencies, mode shapes, and vibration responses obtained from the proposed model, finite element model (FEM), and experiment. The results indicate that the proposed semi-analytical model has high precision and computational efficiency, which can provide an alternative scheme for predicting the vibration characteristics of varying section disk–blades and overcoming the high computational cost of finite element models.

Rotating Casson nanofluid convection for Au, Ag, CuO and Al2O3 nanoparticles embedded by Darcy-Brinkman porous medium

The present study examines convection in a Casson nanofluid layer in a porous media under the effect of Coriolis force using Darcy-Brinkman model. For a variety of metallic and non-metallic nanoparticles, the analysis is conducted by utilizing the linear stability theory, normal mode approach, and one term Galerkin type weighted residual method. When current numerical findings are compared to those that have already been published, good agreements are found for the permitted range of parameters. Blood (Casson fluid) is numerically simulated for porous media using the Mathematica software to make the analysis valuable for practical applications. Top-heavy configuration of nanoparticles is found to lead to a stationary mode of convection. The effect of porous medium, rotation, Casson parameter and nanoparticle parameters is discussed numerically. Interestingly, it is found that though Casson fluids are more stable as compared to regular fluids but Casson parameter itself has a destabilizing effect on the system. The really important and novel result of the study comes out as the fact that Coriolis force can stabilize the gold-nanoparticle-based Casson fluid layer system which is otherwise totally unstable. As far as metallic and non-metallic nanoparticles are concerned; the stability pattern followed by metallic nanofluids is iron-blood>copper-blood>silver-blood>gold-blood and for non-metallic nanofluids is silica-blood> alumina-blood> titanium oxide-blood>copper oxide-blood.

Phase-field lattice Boltzmann model of growth and buoyancy driven motion of dendritic particles: the effect of Coriolis force

A phase-field lattice Boltzmann (PFLB) model we developed recently (Rátkai L, Pusztai T and Gránásy L 2019 npj Comput. Mater. 5 113) was adapted to investigate the effect of Coriolis force on the solidification morphology forming in a centrifuge. The moving particles are handled using an overlapping multi-grid scheme, assigning a separate moving grid to each individual particle, with attached local fields. Relying on this approach, solidification problems, in which solute diffusion, melt flow, solid motion, the effect of gravity and collision of the particles occur simultaneously can be modelled. Using relevant properties of an Al-Ti alloy, the interaction of columnar and equiaxed solidification was studied. It was found that the Coriolis force influences the path of the falling dendritic particles, which in turn governs the position, at which the transition between columnar and equiaxed morphologies takes place.

Exploration of the effects of Coriolis force and thermal radiation on water-based hybrid nanofluid flow over an exponentially stretching plate

Hybrid nanofluids’ enhanced thermophysical properties make them applicable in a plethora of mechanical and engineering applications requiring augmented heat transfer. The present study focuses on a three-dimensional Copper-Aluminium Oxide left( Cutext{- }Al_{2}O_{3}right)-water based hybrid nanofluid flow within the boundary layer with heat transfer over a rotating exponentially stretching plate, subjected to an inclined magnetic field. The sheet rotates at an angular velocity Omega and the angle of inclination of the magnetic field is gamma. Employing a set of appropriate similarity transformation reduces the governing PDEs to ODEs. The resulting ODEs are solved with the finite difference code with Shooting Technique. Primary velocity increases at large rotation but the secondary velocity reduces as the rotation increases. In addition, the magnetic field is found to oppose the flow and thereby causing a reduction in both the primary and secondary velocities. Increasing the volume fraction reduces the skin friction coefficient and enhances the heat transfer rate.

Effect of Coriolis and buoyancy forces on three-dimensional flow of chemically reactive tangent hyperbolic fluid subject to variable viscosity

Thermophoresis effect has wide range of applications in electro-static precipitators and in biology for calculating single biological macro molecules, such as genomic-length DNA and HIV virus in the micro channels. Current study deal with effects of Coriolis and buoyancy forces on the three-dimensional boundary layer flow of tangent hyperbolic fluid with thermo-migration and haphazard motion of nano-sized particles. Arrhenius kind of chemical reaction is taken along an exponentially stretchable surface. The main focus of current exploration is to execute shear thinning nano-liquid flow past an exponentially rotating stretchable surface under the influence of variable viscosity, mixed convection and activation energy. We are motivated to explore the features of three-dimensional shear thinning model combined under the features of mixed convention, variable viscosity, and activation energy. The mathematical model is designed to generate PDEs and converted them into ODEs by employing fractious transformation. The numerical outcomes are exhibited via graphs by employing Bvp4c numerical technique whereas the values of skin friction coefficient are calculated by monopolizing shooting method. Characteristics of the parameters appearing in modeling like the viscosity parameter, power-law index, local Weissenberg number, mix convection parameter, rotation parameter, Prandtl number and chemical reaction parameter are comprehensively analyzed through graphical behavior. The impact of governing parameters on skin friction, heat and mass transfer rates is illustrated through tables. The detail analysis anticipates that the elevation in Weissenberg number and porosity caused decline in velocity. Further, the temperature behaves doppositely analogous to development Prandtl besides the thermophoresis parameter.

Vibration analysis of a porous hollow conical rotor with circumferentially distributed piezoceramic strips

The present study investigates vibrational behavior of a porous conical hollow rotor. Inner and outer rotor surface, sensor, and actuator strips made of piezoceramic are modeled and positioned, which are symmetrically distributed in the circumferential direction. Kinetic and potential energies were computed considering the effects of Coriolis and centrifugal force. Modeling of the system has been carried out assuming classical theory and using Lagrange approach for simple-supported boundary conditions. Also, the relations of piezoceramic and three types of porosity attend in equilibrium equations. The discretization of kinetic and potential energies using displacement field which is defined as double mixed series based on independent mode shape and time function leads to obtaining the equations in form of ordinary differential. To calculate the natural frequencies, the equations were converted to a special form of state space model. The correctness of the study is examined by comparing it with similar study results. The most consequential parameters affecting the forward and backward natural frequency, such as type and porosity coefficient, size, number, and thickness of piezoceramic, and the rotor angular velocity, are researched. The results demonstrate that the effect of porosity coefficient in various longitudinal modes on natural frequency is different.

Axial force contribution to the out-of-plane response of horizontally curved beams under a moving mass excitation

Horizontally curved beams subjected to a moving mass do experience a time-varying axial force due to the in-plane centrifugal action of the inertial accelerations. The current study aims at investigating the contribution of the induced axial force to the out-of-plane dynamics of horizontally curved beams under the excitation of a moving mass. The governing differential equations of motion are established to account for the action of the axial force, and also the effect of mass inertia, Coriolis and centrifugal forces introduced by a moving object. In the course of dealing with the semi-analytical approach, a new system of ordinary differential equations is distilled utilizing the transition matrix method in order to be amenable for numerical computations. The veracity of the solution has been corroborated through comparison with the results attained by the previous studies addressed in the literature. Moreover, the efficiency of the proposed solution is demonstrated through conducting an extensive parametric study. In that regard, the dynamic impact factor spectra have been obtained for various design parameters including the geometrical and dynamic properties of the system. The findings reveal that, in general, the dynamic impact factor is highly affected by the mass and velocity of the moving object. Furthermore, the results indicate that the inclusion of the axial force can result in a reduction in the dynamic impact factor spectra, which is shown to be more substantial for the response evaluation of short-span horizontally curved beams excited by a high-velocity heavy mass. In this particular situation, the mitigating effect of the axial force becomes comparable to that of the foundation damping. This paper concludes with an investigation on the influence of the axial force on the time-history patterns, which is demonstrated to attenuate the response amplitudes at both the forced and free vibration phases.

Elliptically polarized attosecond pulse generation by corotating bicircular laser fields

We revisit high-order-harmonic generation (HHG) in corotating bicircular fields, which possess high optical chirality, and extend the study to a frequency ratio higher than 1:2. By analyzing the classical trajectories in the corotating bicircular fields in the rotating frame, we show that the Coriolis-force effect that hinders HHG decreases with the frequency ratio. Given these features, we propose a method for producing highly elliptically polarized attosecond pulses (with ellipticity up to $\ensuremath{\epsilon}=0.88$) using the corotating bicircular field with a frequency ratio of 1:3. A comparison is also made with the extensively studied counter-rotating configurations with a frequency ratio of 1:2 considering various laser parameters. The results affirm the validity and superiority of the corotating configurations, from which both the ellipticity and yield of generated attosecond pulses are higher than those from the counter-rotating configurations.

Thickness Configuration Effect on Frequency and Critical Speed of Spinning Variable-Thickness Cylindrical Shells

The thickness configuration effect on natural frequency and critical speed of spinning variable-thickness cylindrical shells is investigated in this paper. Based on Love’s thin shell theory, the eigenfrequency equation is derived by employing the Rayleigh–Ritz method in conjunction with Chebyshev polynomials, considering the effects of Coriolis and centrifugal forces due to rotation. Seven types of thickness configurations and various classical boundary conditions are taken into account. Backward and forward wave frequencies, the critical speed, and the mode shapes of the spinning variable-thickness cylindrical shells are solved. Results show that the thickness configuration not only changes circumferential wave number corresponding to the lowest natural frequency, but also affects the critical speed. However, the influence of thickness configuration on mode shapes of the shell is not obvious. The stronger the boundary constraints, the more obvious effect of slope of thickness variation on the critical speed of spinning cylindrical shells.

Meshless Chebyshev RPIM Solution for Free Vibration of Rotating Cross-Ply Laminated Combined Cylindrical-Conical Shells in Thermal Environment.

This paper provides a numerical solution to the vibration of a rotating cross-ply laminated combined conical-cylindrical shell in the thermal environment. Its numerical discrete solution method uses the meshless method. The combined shell assumed the temperature independence of material property is divided to the fundamental conical and cylindrical shell substructures, and the theoretical formulation for each substructure is derived based on the first order shear deformation theory (FSDT) and Hamilton’s principle. The effects of the initial hoop tension and temperature change are considered through the kinetic energy reflecting the effects of centrifugal and Coriolis forces and additional strain energy by the nonlinear part of the Green–Lagrange strains. The substructures are then assembled according to the continuity conditions. The boundary and continuity conditions are simulated by introducing artificial virtual spring technology. The displacement component in the theoretical formulation is approximated using a meshless Chebyshev-RPIM shape function. The reliability of the method is verified by comparing with mature and reliable results. The free vibration characteristics of the rotating combined conical-cylindrical shell structure under various sizes, speeds and temperatures are given by numerical examples.

Effects of Mass Variation in the Collinear Perturbed Moulton-Copenhagen Configuration

The main idea of this paper is to investigate the motion properties of the smallest body under the gravitational forces of the three collinear spherical primaries. Here we place the three primaries on the same line where the masses of two primary bodies are taken equal and third primary body is having the solar radiation effect. The effects of Coriolis and centrifugal forces on the system is considered. Therefore this system is recognized as collinear perturbed Moulton-Copenhagen configuration. After determining the equations of motion and quasi-Jacobi integral, we numerically illustrate the locations of equilibrium points (in-plane and out-of-plane), regions of motion, Poincaré surfaces of section, basins of attraction and periodic orbits. And then the examination of stability for the equilibrium points lie either in-plane or out-of-plane are examined.

Study on the Flow Boiling Heat Transfer Characteristics of the Liquid Film in a Rotating Pipe

A three-dimensional numerical model is established to study the flow boiling heat transfer characteristics of the liquid film in a rotating pipe, and the effectiveness of the model is verified by a comparison between the numerical results and the experimental results. The effects of rotational speed, heat flux, and Coriolis force on the characteristics of heat transfer of the rotating liquid film are investigated. The conclusions are drawn as follows: (1) The convection of the rotating liquid film is enhanced while the nucleate boiling in the rotating liquid film is inhibited by the increase in the rotational speed; (2) With the influence of these two factors, the heat transfer coefficient increases with centrifugal acceleration increasing from 20 g to 40 g, then decreases with centrifugal acceleration increasing from 40 g to 120 g; (3) The turbulent intensity of the flow with Coriolis force is obviously increased compared to that without Coriolis force when the centrifugal acceleration ranges from 20 g to 80 g, which shows no increase at higher centrifugal accelerations when the turbulence is sufficiently strong. The Coriolis force also has an impact on the heat transfer coefficient of the liquid film, which should not be ignored when studying the boiling heat transfer of a rotating liquid film.

Effect of Coriolis Force on the Numerical Estimation of Water Level Elevation Due to a Catastrophic Cyclone along the Coast of Bangladesh

A two-dimensional vertically integrated shallow water equation in the Cartesian coordinate model is used to estimate the water level considering the impact of Coriolis force. The shallow water model equation was discretized by a finite difference method (FDM). Consider the forwarding of time and central space as a moderator of this discretization. The model approximates coastal boundaries, small islands, small rivers and complex tributaries by an accurate stair step representation. The model equations are solved by a static semi-implicit finite difference technique where a structured Arakawa C-grid system is used as the condition. A one-way nested scheme technique is used to incorporate complex land-sea interfaces such as small offshore islands and water depths with sufficient accuracy as well as decreasing the computational cost. A stable tidal condition was created by applying M2 tidal forcing with the largest tide along the southern open boundary of the Bay of Bengal. The model uses the Coriolis force as an external force that can affect water buoyancy. The main task is to analyse the effect of Coriolis force on water buoyancy. The described model was applied to simulate sea-surface elevation associated with the severe cyclone in April 1991 that strike on the east coast of Bangladesh. We have found a significant impact of Coriolis force on surge height. However, the model gives an accurate numerical estimate of surge height.