Coupling Of Motion Research Articles

Comprehensive analysis of heavy-ion fusion reactions around the Coulomb barrier

We have investigated the fusion dynamics of 12C + 92Zr, 16O + 92Zr, 28Si + 92Zr, 35Cl + 92Zr, 16O + 60Ni, 18O + 58Ni, 12C + 194,198Pt, 16O + 144,148,154Sm and 17O + 144Sm reactions in the close vicinity of the Coulomb barrier. For this purpose, we have opted one-dimensional Wong formula, coupled channel approach, and symmetric-asymmetric Gaussian barrier distribution (SAGBD) model to analyze the fusion data for above mentioned reactions. For all studied systems, the theoretical results obtained from the one-dimensional Wong formula are unable to reproduce the fusion data especially at incident energies lying below the nominal barrier. This appeals for the inclusion of intrinsic degrees of freedom which have been originated from the nuclear structure of fusing nuclei, and thus essentially required to explain the experimental data at energies lying in the sub-barrier realm. For the chosen reactions, the coupled channel analysis suggests that the coupling of relative motion with the inelastic surface excitations and/or nucleon transfer channels associated with the reaction partners have produced a remarkable fusion enhancement at energies lying near and below the nominal barrier. It is particularly intriguing that the SAGBD model can replicate the impacts of dominant intrinsic reaction channels such as multi-phonon quantum states and/or nucleon transfer channels via Gaussian type of weight function. The predictions of the SAGBD approach appropriately reproduce the fusion cross-sections data and related barrier distributions data for the selected reactions due the fact that the multi-dimensional nature induces the barrier lowering effects and subsequently reduces the effective fusion barrier between the participants. In the SAGBD approach, the channel coupling effects are quantitively measured in terms of channel coupling parameter and percentage decrement in height of effective fusion barrier with respect to the Coulomb barrier Furthermore, the recovered -values for selected reactions are found to be smaller and hence clearly demonstrate the applicability of the model outcomes to explore the fusion dynamics of the studied systems.

Kinematic coupling of the glenohumeral and scapulothoracic joints generates humeral axial rotation

Glenohumeral and scapulothoracic motion combine to generate humerothoracic motion, but their discrete contributions towards humerothoracic axial rotation have not been investigated. Understanding their contributions to axial rotation is important to judge the effects of pathology, surgical intervention, and physiotherapy. Therefore, the purpose of this study was to investigate the kinematic coupling between glenohumeral and scapulothoracic motion and determine their relative contributions towards axial rotation. Twenty healthy subjects (10 M/10F, ages 22–66) were previously recorded using biplane fluoroscopy while performing arm elevation in the coronal, scapular, and sagittal planes, and external rotation in 0° and 90° of abduction. Glenohumeral and scapulothoracic contributions towards axial rotation were computed by integrating the projection of glenohumeral and scapulothoracic angular velocity onto the humeral longitudinal axis, and analyzed using one dimensional statistical parametric mapping and linear regression. During arm elevation, scapulothoracic motion supplied 13–20° (76–94%) of axial rotation, mainly via scapulothoracic upward rotation. The contribution of scapulothoracic motion towards axial rotation was strongly correlated with glenohumeral plane of elevation during arm elevation. During external rotation, scapulothoracic motion contributed 10° (8%) towards axial rotation in 0° of abduction and 15° (15%) in 90° of abduction. The contribution of scapulothoracic motion towards humerothoracic axial rotation could explain the simultaneous changes in glenohumeral plane of elevation and axial rotation associated with some pathologies and surgeries. Understanding how humerothoracic motion results from the functional coupling of scapulothoracic and glenohumeral motions may inform diagnostic and treatment strategies by targeting the source of movement impairments in clinical populations.

Interaction between surfaces decorated with like-charged pendants: Unravelling the interplay between energy and entropy leading to attraction

HypothesisThe stronger motional coupling between monovalent counterions neutralizing homogeneously like-charged surfaces induced by an increase in charge density is known to foster inter–surface attraction. Compared to a uniformly distributed charge, point-like charges generate locally more intense fields, so that the correlation induced between counterions may be even stronger despite an identical total charge. It should thus be possible to induce surface attraction at lower charge densities than commonly expected. ExperimentsMonte Carlo simulations on primitive electrolyte models have been exploited to compute potential of mean force profiles and mobile ion densities for systems composed of two parallel surfaces bearing surface-tethered monovalent like-charged pendants as a function of the surface distance and pendant densities. FindingsSurfaces bearing like-charged pendants are found to attract each other over a wide range of distances despite the presence of very low charge densities. Notwithstanding the attractive contribution to the inter-surface forces provided by electrostatic interactions, the entropic component of the system Helmholtz energy is found to play the key role in defining the overall magnitude. The latter finding appears justified by an increase in the relative delocalization of counterions upon decreasing the surface distance.

Influence of pitching motion on the hydrodynamic performance of a horizontal axis tidal turbine considering the surface wave

A CFD numerical method is established under the wave-current condition, used to analyze the hydrodynamic performance of a horizontal-axis tidal turbine based on floating platform with rotation and pitching motion. The inflow direction load, pitch moment and power coefficients with different depths of the blade tip-immersion, the periods and amplitudes of the pitch, wave heights are obtained. The three coefficients have obvious periodically fluctuated with the pitching and wave frequencies, while the time mean of those have changed little with increasing of the depth of blade tip-immersion, wave height, pitch (wave) period and pitching amplitude. So considering damping and additional mass forces, a load fitting model is established, and the damping and additional mass coefficients are calculated by the least square method. The influence of damping coefficient on the hydrodynamic loads is obvious, while the influence of additional mass coefficient on that can be neglected, and the damping coefficient of inflow direction load coefficient is basically stable. The damping coefficients of the pitching moment and power coefficients fluctuate periodically, but the mean value of damping coefficients keep stable. The research results in this paper are important for studying the coupling motion of the turbine and the floating platform.

Observation of Arginine Side-Chain Motions Coupled to the Global Conformational Exchange Process in Deubiquitinase A

Coupled motions have been demonstrated to be functionally important in a number of enzymes. Noncovalent side-chain interactions play essential roles in coordinating the motions across different structural elements in a protein. However, most of the dynamic studies of proteins are focused on backbone amides or methyl groups in the side chains and little is known about the polar and charged side chains. We have previously characterized the conformational dynamics of deubiquitinase A (DUBA), an isopeptidase, on the microsecond-to-millisecond (μs–ms) time scales with the amide 1H Carr–Purcell–Meiboom–Gill (CPMG) experiment. We detected a global conformational exchange process on a time scale of approximately 200 μs, which involves most of the structural elements in DUBA, including the active site and the substrate binding interface. Here, we extend our previous study on backbone amides to the arginine side-chain Nε–Hε groups using a modified 1H CPMG pulse sequence that can efficiently detect both backbone amide and arginine side-chain Nε–Hε signals in a single experiment. We found that the side chains of three arginines display motions on the same time scale as the backbone amides. Mutations of two of the three arginines to alanines result in a decrease in enzyme activity. One of these two arginines is located in a loop involved in substrate binding. This loop is not visible in the backbone amide-detected experiments due to excess line broadening induced by motions on the μs–ms time scales. These results clearly demonstrate that the motions of some arginine side chains are coupled to the global conformational exchange process and provide an additional probe for motions in a functionally important loop that did not yield visible backbone amide signals, suggesting the value of side-chain experiments on DUBA. The modified 1H CPMG pulse sequence allows the simultaneous characterization of backbone and arginine side-chain dynamics without any increase in data acquisition time and can be applied to the dynamic studies of any protein that displays measurable amide 1H relaxation dispersion.

Development of a cross-scale 2-DOF piezoelectric rotary platform based on active friction switching

In order to overcome the typical cross-scale motion contradiction between the large motion range (radian scale) and high displacement resolution (microradian scale) in single actuation device, we proposed a novel two degrees of freedom (2-DOF) piezoelectric rotary platform (PERP) to implement cross-scale rotary motions based on active friction switching. A longitudinal-bending-bending (LBB) piezoelectric actuator (PEA) was developed to realize 2D lateral bending motions and 1D longitudinal motion. The former was used to drive rotor, while the latter was employed to implement friction switching. The principles of the PERP and the switching mechanism of the working modes were illustrated systematically. The finite element method (FEM) was utilized to simulate the motions of the PEA, and a series of experimental results successfully verified the principles and the theoretical analyses. The 2-DOF cross-scale rotary motions were successfully realized, and the PERP can achieve large motion range of 2π rad, maximum rotary velocity of 817.88 mrad/s, high resolution of 23.03 μrad and low coupling motion of 4.91%. The proposed friction switching method held benefits to improve flexibility and stable frequency range (more than 10 times) of dynamic scanning motion. The developed PERP could be used to drive optical mirrors with merits of both large motion range and high resolution for multiple target tasks.

Memory effects in spiral diffusion of rotary self-propellers

The coupling of deterministic rotary motion and stochastic orientational diffusion of a self-propeller leads to a spiral trajectory of the expected displacement. We extend our former analysis of spiral diffusion [Phys. Rev. E 94, 030601(R) (2016)10.1103/PhysRevE.94.030601] in the white-noise limit to a more realistic scenario of stochastic noise with Gaussian memory and orientational fluctuations driven by an Ornstein-Uhlenbeck process. A variety of dynamical regimes including crossovers from ballistic to diffusive to ballistic in the angular dynamics are determined by the inertial timescale, orientational diffusivity, and angular speed.

Universal energy-dependent pseudopotential for the two-body problem of confined ultracold atoms

The two-body scattering amplitude and energy spectrum of confined ultracold atoms are of fundamental importance for both theoretical and experimental studies of ultracold-atom physics. For many systems, one can efficiently calculate these quantities via the zero-range Huang-Yang pseudopotential (HYP), in which the interatomic interaction is characterized by the scattering length $a$. Furthermore, when the scattering length is dependent on the kinetic energy ${\ensuremath{\varepsilon}}_{\mathrm{r}}$ of two-atom relative motion, i.e., $a=a({\ensuremath{\varepsilon}}_{\mathrm{r}})$, the results are applicable for a broad energy region. However, when the free Hamiltonian of atomic internal state (e.g., the Zeeman Hamiltonian) does not commute with the interatomic interaction, or the center-of-mass (c.m.) motion is coupled to the relative motion, the generalization of this technique is still lacking. In this work we solve this problem and construct a reasonable energy-dependent multichannel HYP, which is characterized by a ``scattering length operator'' ${\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{a}}_{\mathrm{eff}}$, for the above complicated cases. Here, ${\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{a}}_{\mathrm{eff}}$ is an operator for atomic internal states and c.m. motion, and depends on both the total two-atom energy and the external field as well as the trapping parameter. The effects from the internal-state or c.m.-relative motion coupling can be self-consistently taken into account by ${\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{a}}_{\mathrm{eff}}$. We further show a method based on the quantum defect theory, with which ${\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{a}}_{\mathrm{eff}}$ can be analytically derived for systems with van der Waals interatomic interaction. To demonstrate our method, we calculate the spectrum of two ultracold fermionic alkaline-earth-like atoms [in electronic $^{1}S_{0}$ $(|g\ensuremath{\rangle})$ and $^{3}P_{0}$ $(|e\ensuremath{\rangle})$ states, respectively] confined in an optical lattice. By comparing our results with the recent experimental measurements for two $^{173}\mathrm{Yb}$ atoms and two $^{171}\mathrm{Yb}$ atoms, we calibrate the scattering lengths ${a}_{\ifmmode\pm\else\textpm\fi{}}$ with respect to antisymmetric and symmetric nuclear-spin states to be ${a}_{+}=2012(19){a}_{0}$ and ${a}_{\ensuremath{-}}=193(4){a}_{0}$ for $^{173}\mathrm{Yb}$, and ${a}_{+}=232(3){a}_{0}$ and ${a}_{\ensuremath{-}}=372(1){a}_{0}$ for $^{171}\mathrm{Yb}$.

Self-Sustained Collective Motion of Two Joint Liquid Crystal Elastomer Spring Oscillator Powered by Steady Illumination.

For complex micro-active machines or micro-robotics, it is crucial to clarify the coupling and collective motion of their multiple self-oscillators. In this article, we construct two joint liquid crystal elastomer (LCE) spring oscillators connected by a spring and theoretically investigate their collective motion based on a well-established dynamic LCE model. The numerical calculations show that the coupled system has three steady synchronization modes: in-phase mode, anti-phase mode, and non-phase-locked mode, and the in-phase mode is more easily achieved than the anti-phase mode and the non-phase-locked mode. Meanwhile, the self-excited oscillation mechanism is elucidated by the competition between network that is achieved by the driving force and the damping dissipation. Furthermore, the phase diagram of three steady synchronization modes under different coupling stiffness and different initial states is given. The effects of several key physical quantities on the amplitude and frequency of the three synchronization modes are studied in detail, and the equivalent systems of in-phase mode and anti-phase mode are proposed. The study of the coupled LCE spring oscillators will deepen people’s understanding of collective motion and has potential applications in the fields of micro-active machines and micro-robots with multiple coupled self-oscillators.

Active seismotectonics of the East Anatolian Fault

SUMMARYThe East Anatolian Fault (EAF) is a 700-km-long left-lateral transform fault located between the Anatolian and Arabian plates. The proximity of the Euler Pole to the Arabia–Anatolia Plate boundary leads to rapid changes in plate velocity along the boundary, which is manifested by the decreasing slip rates from east (10 mm yr–1) to west (∼1–4 mm yr–1). The EAF displays heterogeneous seismicity patterns with seismic gaps, localized clusters and broad diffuse zones. In this study, in order to understand the origin of these complexities and quantify the seismic hazard along the EAF, we present an improved seismicity catalogue with more than 26 000 earthquakes and 160 focal mechanisms from regional moment tensor inversion between 2007 and 2020. The focal mechanisms and seismicity show that the EAF dips towards north and forms a well-defined plate boundary in the east between Palu and Çelikhan with almost pure left-lateral motion. Further west, the boundary becomes broader with activity along subparallel faults. Focal mechanisms show heterogeneous stress orientations in consistence with geodetically determined strain rate field. The stress orientations show a transition from strike-slip to extension towards the west of Çelikhan. Amongst all segments of EAF, the Pütürge segment, which holds the near-repeating earthquakes in the vicinity of the nucleation of the 2020 Mw 6.8 earthquake, is distinguished with its steady and high rate of seismicity. Further east, the neighbouring Palu segment is characterized by several distinct moderate earthquakes. We do not observe any change in the seismicity rate on these segments of the EAF following large earthquakes. In order to quantify the seismic hazard along the EAF, we calculate the recurrence time and maximum magnitude for each segment by using an extended seismicity catalogue of 150 yr including the large historical earthquakes and the geodetic strain rate. The results show ∼150 yr recurrence time with Mmax∼6.7–7.0 along the seismically active Palu and Pütürge segments on the east, while relatively silent western segments yield longer recurrence times; 237–772 for Pazarcık and 414–917 for Amanos segments with slightly larger magnitudes (Mmax ∼7–7.4). We infer that the seismicity patterns and strain-rate field along the EAF are shaped by several factors such as strong geometrical irregularities, heterogeneous coupling and complex plate motion leading to rapid change of fault slip rate.

Optomechanical strong coupling between a single photon and a single atom

Single atoms coupled to a cavity offer unique opportunities as quantum optomechanical devices because of their small mass and strong interaction with light. A particular regime of interest in optomechanics is that of ‘single-photon strong coupling’, where motional displacements on the order of the zero-point uncertainty are sufficient to shift the cavity resonance frequency by more than its linewidth. In many cavity QED platforms, however, this is unfeasible due to the large cavity linewidth. Here, we propose an alternative route in such systems, which instead relies on the coupling of atomic motion to the much narrower cavity-dressed atomic resonance frequency. We discuss and optimize the conditions in which the scattering properties of single photons from the atom-cavity system become highly entangled with the atomic motional wave function. We also analyze the prominent observable features of this optomechanical strong coupling, which include a per-photon motional heating that is significantly larger than the single-photon recoil energy, as well as mechanically-induced oscillations in time of the second-order correlation function of the emitted light. This physics should be realizable in current experimental setups, such as trapped atoms coupled to photonic crystal cavities, and more broadly opens the door to realizing qualitatively different phenomena beyond what has been observed in optomechanical systems thus far.

Kinematic Simulation and Experimental Research for an Under-actuated Joint Group

Considering the problems of the existing joint group for continuous manipulator, including that it is unrealized to meet the required length of the manipulator and the large bending angle of the joint, a new type of under-actuated linkage joint group is proposed in this paper. The parameterized models of the joint group based on the elastic deformation of the linkage rope and the variable-diameter transmission wheel are established respectively, and the kinematics mapping model of the joint group is derived. Based on the establishment of the model, simulation verification was carried out by applying Adams. Finally, the proposed joint group and kinematics model was verified through experiments. The research results show that the total length of the joint group is 750mm, the maximum movement angle of a single joint in the joint group is greater than 30°, and the maximum movement angle of the joint group is greater than 90°, which improves the maximum movement space and maximum movement angle of the existing joint group. Besides, the joint group can realize the coupling motion of three joints.

CFD Simulation and Experimental Study on Coupled Motion Response of Ship with Tank in Beam Waves

Tank sloshing is widely present in many engineering fields, especially in the field of marine. Due to the trend of large-scale liquid cargo ships, it is of great significance to study the coupled motion response of ships with tanks in beam waves. In this study, the CFD (Computational Fluid Dynamics) method and experiments are used to study the response of a ship with/without a tank in beam waves. All the computations are performed by an in-house CFD solver, which is used to solve RANS (Reynold Average Navier-Stokes) equations coupled with six degrees-of-freedom solid-body motion equations. The Level Set Method is used to solve the free surface. Verification work on the grid number and time step size has been conducted. The simulation results agree with the experimental results well, which shows that the numerical method is accurate enough. In this paper, several different working conditions are set up, and the effects of the liquid height in the tank, the size of the tank and the wavelength ratio of the incident wave on the ship’s motion are studied. The results show the effect of tank sloshing on the ship’s motion in different working conditions.

Dynamic modeling of rotating blades system based on transfer matrix method of multibody system

Due to the coupling between the stator and the blades, the vibration characteristics of rotating blades play an important role in the structural reliability of rotating machinery. The computational modeling challenge lies in achieving the coupling of the rotating bending-torsional blade with the stator. To perform rapid and accurate vibration characteristics analysis, the Transfer Matrix Method of Multibody System (MSTMM) is proposed to study the multibody dynamics models of single rotating beam and rotor-stator coupled system. The models are verified by comparison with finite element method (FEM) results. Using the beam model, rotating blades pure bending and torsion frequencies can be simply computed, these are the key parameters for establishing critical instability dynamic models, such as 2D aerofoil or blade flutter models. By computing the vibration characteristics with varying rotating speed, the influence of the blade rotation is illustrated. The computational results show that, the influence of rotation is greater on the frequencies associated with the bending rather than with the one of the torsion mode, hence the adjacent natural frequencies may intersect. At the veering point, the mode shape of bending-torsion coupling mode changes greatly, compared with that of other rotation speeds. In addition, asymmetric modes can be observed in the rotor-stator coupled model due to the coupling of elastic deformation and rigid body motion. The modeling process is simple and rapid, only assembling the transfer matrix of each element like building blocks. This proposed model can be applied to compute coupled/uncoupled bending-torsional frequencies of helicopter and wind turbine blades, and the results can provide useful guidance for the modeling of rotating machinery.

Comparative Functional Morphology of Human and Chimpanzee Feet Based on Three-Dimensional Finite Element Analysis.

To comparatively investigate the morphological adaptation of the human foot for achieving robust and efficient bipedal locomotion, we develop three-dimensional finite element models of the human and chimpanzee feet. Foot bones and the outer surface of the foot are extracted from computer tomography images and meshed with tetrahedral elements. The ligaments and plantar fascia are represented by tension-only spring elements. The contacts between the bones and between the foot and ground are solved using frictionless and Coulomb friction contact algorithms, respectively. Physiologically realistic loading conditions of the feet during quiet bipedal standing are simulated. Our results indicate that the center of pressure (COP) is located more anteriorly in the human foot than in the chimpanzee foot, indicating a larger stability margin in bipedal posture in humans. Furthermore, the vertical free moment generated by the coupling motion of the calcaneus and tibia during axial loading is larger in the human foot, which can facilitate the compensation of the net yaw moment of the body around the COP during bipedal locomotion. Furthermore, the human foot can store elastic energy more effectively during axial loading for the effective generation of propulsive force in the late stance phase. This computational framework for a comparative investigation of the causal relationship among the morphology, kinematics, and kinetics of the foot may provide a better understanding regarding the functional significance of the morphological features of the human foot.

Development of dual-arm mobile robot platform based on ROS

Background: With the increasing demand of mobile robots in warehousing, logistics and service fields, simple planar motion is difficult to meet the task requirements of complex environment. The combination of mobile robot and cooperative robot is helpful to improve the dexterity of robot movement and expand the application of robots. Methods: Aiming at the application requirements of dual-arm robots and mobile robots in practical applications, this paper designed the hardware of a platform, built a simulation platform based on ROS (Robot Operating System), and designed the actual software control framework. Finally, the feasibility of the platform design was verified by the coupling motion experiment of the two robots. Results: We have established a simulation of the dual-arm mobile platform in ROS, designed the actual software control framework, and verified the feasibility of the platform design through experiments. Conclusions: The mobile platform can meet a variety of application requirements and lay the foundation for subsequent development.

Emission spectroscopy of NaYF4:Eu nanorods optically trapped by Fresnel lens fibers

NaYF 4 : Eu nanorods with high aspect ratios are elaborated and optically trapped using dual fiber optical tweezers in a counterpropagating geometry. High trapping efficiency is observed using converging beams, emitted from diffractive Fresnel lenses directly 3D printed onto cleaved fiber facets. Stable nanorod trapping and alignment are reported for a fiber-to-fiber distance of 200 μm and light powers down to 10 mW. Trapping of nanorod clusters containing one to three nanorods and the coupling of nanorod motion in both axial and transverse directions are considered and discussed. The europium emission is studied by polarization-resolved spectroscopy with particular emphasis on the magnetic and electric dipole transitions. The respective σ and π orientations of the different emission lines are determined. The angles with respect to the nanorod axes of the corresponding magnetic and electric dipoles are calculated. Mono-exponential emission decay with decay time of 4–5 ms is reported. It is shown that the nanorod orientation can be determined by purely spectroscopic means.

The Contributions of Model Studies for Fundamental Understanding of Polymer Mechanochemistry

AbstractThe exciting field of polymer mechanochemistry has made great empirical progress in discovering reactions in which a stretching force accelerates scission of strained bonds using single molecule force spectroscopy and ultrasonication experiments. Understanding why these reactions happen, i.e., the fundamental physical processes that govern coupling of macroscopic motion to chemical reactions, as well as discovering other patterns of mechanochemical reactivity require complementary techniques, which permit a much more detailed characterization of reaction mechanisms and the distribution of force in reacting molecules than are achievable in SMFS or ultrasonication. A molecular force probe allows the specific pattern of molecular strain that is responsible for localized reactions in stretched polymers to be reproduced accurately in non-polymeric substrates using molecular design rather than atomistically intractable collective motions of millions of atoms comprising macroscopic motion. In this review, we highlight the necessary features of a useful molecular force probe and describe their realization in stiff stilbene macrocycles. We describe how studying these macrocycles using classical tools of physical organic chemistry has allowed detailed characterizations of mechanochemical reactivity, explain some of the most unexpected insights enabled by these probes, and speculate how they may guide the next stage of mechanochemistry.

Real‐time predictive control‐based anti‐pitching method for high‐speed multihull with appendages constraints

AbstractIn order to mitigate the excessive amplitudes of pitch and heave motions, a real‐time predictive control method is proposed for the high‐speed multihull with strict input constraints of anti‐pitching appendages. The vertical control model of the high‐speed multihull has been established with T‐foil and flap served as anti‐pitching appendages, and the motion couplings between heave and pitch have been analyzed. The wave disturbance considered as a kind of colored noise can be whitened so as to obtain the control signal, and then adaptive extended Kalman filtering method can be used to get the online estimates of the heave velocity and pitch angular velocity. The proposed predictive control‐based anti‐pitching method mainly contains two reformed aspects of the predictive control. One is to take into account the error between the actual and predicted system values, such that the prediction model with linear error correction can be obtained resulting in the enhanced robustness. The other is to employ the Laguerre function to convert the control sequence of moving horizon optimization into the fewer‐dimensional Laguerre parameters, and then the computational burden of online optimization can be significantly reduced indicating the improved real‐time performance. The closed‐loop system stability has also been theoretically analyzed. The simulation and experiment have been carried out to verify the effectiveness of the proposed algorithm in this paper.

A comparison of the pulsating and steady jets on flow-induced vibrations and thermal behavior of a sprung cylinder inside an isothermal channel

In this paper, the effect of the pulsating jet from channel walls on the thermal and vibrational behavior of the elastically-mounted cylinder is examined. For the sake of comparison, the efficiency of the steady jet in which the injection velocity is constant has also been taken into account. The primary parameters studied are jet distance, pulsating jet velocity, and frequency. The finite volume method is used to solve flow and energy equations. The dynamic mesh approach is also utilized for the cylinder's motion coupling with a flow field. The results of fluid-solid interaction simulations demonstrate that the pulsating jet acts very successfully in reducing cylinder vibrations, so that at Uj=2, The maximum cylinder displacement magnitude is reduced by 91%, 94%, and 94% for slots 1, 2, and 3, respectively. On the other hand, to reduce the cylinder displacement by the steady jet, the injection velocity must be large enough in which the efficiency decreases significantly as the jet distance increases. The primary reason for the vibration reduction in the steady jet is to suppress the vortex shedding behind a circular cylinder. However, as the jet distance increases, the ability of the steady jet to make changes to vortices decreases, and for this reason, no significant difference in the cylinder displacement magnitude is observed for slot 3. In contrast, the main mechanism for reducing vibrations in a pulsating jet is to change the vortex shedding frequency. Consequently, the cylinder comes out the lock-in region, and the displacement magnitude is reduced independently of jet injection from triple slots.