جستجوی مقالات مرتبط با کلیدواژه "fluid-solid interaction" در نشریات گروه "مکانیک"

Leveraging artificial intelligence to forecast heat transfer characteristics across diverse industries holds significant potential for improving thermal equipment design, increasing heat transfer efficiency, optimizing cooling systems, and reducing energy consumption. The main contribution and purpose of the current study is predicting the Nusselt number in the context of turbulent flow-induced vibration around a heated cylinder experiencing unconfined oscillations along both streamwise and transverse axes. The anticipation of the Nusselt number relies on transverse and streamwise displacements of the oscillating cylinder and encompasses three distinct scenarios: displacement input in the x-direction, displacement input in the y-direction, and comprehensive amalgamation of both x and y inputs. This prediction is achieved through a sophisticated deep long short-term memory network, meticulously crafted and fine-tuned using a particle swarm optimization algorithm. The results highlight the effectiveness of the optimized networks across various inputs, with the highest predictive precision observed when employing combined x and y inputs. The correlation coefficients within the test segment are as follows: 0.967 for x input, 0.961 for y input, and 0.975 for combined x and y inputs. By applying the methodology elucidated in this study, the forecasting of heat transfer characteristics for structures subjected to fluid flow emerges as a feasible possibility.

The fluid-solid interaction of forced convective flow around a circular cylinder within a channel is investigated. All the channel surfaces are insulated, and the cylinder has heat transfer with the cold passing flow at a constant temperature. The lower surface of the channel is rigid, while the upper part is elastic. Crossing the flow into the hot surface and vibrating the elastic shell cause the heat transfer rate of the cylinder to change. The changes depend on the vibration conditions of the elastic oscillator. It was found that the location of the elastic surface, vibrational amplitude and frequency are the most significant factors affecting the exit flow temperature of the channel. The variation of main parameters (elastic surface location, amplitude and frequency) which affect the flow pattern was investigated. Studies at five different Reynolds shows that replacing the elastic wall on the cylinder upstream has a more significant effect on increasing heat transfer compared to the cylinder downstream. The results also indicate a growth in average Nusselt number by rising the vibrational amplitude and frequency.

In this study, the effect of replacing the elastic wall in a two-dimensional channel for forced convection flow around a circular cylinder surrounded by an incompressible flow has been studied numerically. As the current passes around the hot cylinder and the elastic wall oscillates, the rate of heat transfer changes at any time, which is a function of the vibration conditions of the elastic oscillator. Amplitude, frequency and vibration mode are the main parameters affecting the current passing through the channel. The2refore, in this study, the effect of oscillator vibration in the first, second and third modes has been investigated and in each mode, three different amplitudes and in each amplitude three different frequencies have been investigated and the calculations for two Reynolds numbers 100 and 200 have been solved. Rigid channels are compared. The results show that in the first mode, unlike the second and third modes, the elastic wall oscillation has a great effect on the average Nusselt number, average output temperature and cylinder drag coefficient. in all modes, with increasing amplitude and frequency, the average Nusselt number, the average output temperature and the drag coefficient of the cylinder increase.

Numerical simulation of Eulerian fluid Lagrangian solid interaction incorporating H2-O2 mixture gas detonation plate forming by employing conservative element and solution element immersed boundary method in LS-DYNA software is proposed in this paper. The detonation mechanism includes 7 species and 16 reactions. The chemical reaction mechanism and detonation wave propagation of Eulerian solver and dynamic plastic response of mild steel thin plate of Lagrangian solver are discussed thoroughly. The Johnson-Cook phenomenological material model with failure criterion is used to provide accurate predictions of dynamic response and failure state of detonation loaded steel plates taking into account material strain-rate sensitivity and non-linearities. The 2D numerical model is validated by comparing the simulation results with experimental data for thickness strain. The simulated pressure-time history of combustion cylinder, von Mises stress and deflection pattern of plate are also represented. Furthermore, a series of numerical simulation was carried out to determine the effect of the magnitude of internal detonation pressure on plate, taking into account different combustion cylinder longitudinal capacities, pre-detonation pressures and ignition point locations. Results show that an increase of pre-detonation pressure is conducive to increase the value of maximum detonation pressure while decreasing the combustion duration. Moreover, combustion cylinder with higher longitudinal capacity is more powerful to deform the plate.

In the nuclear fuel assembly, the mixing vanes are solid components which are attached to the spacer grid. These vanes would increase heat transfer rate from the fuel wall. The force induced by flow may expose the vanes to excessive stress and bending, which in turn, it impairs the mixing vanes. In order to improve the heat transfer rate and decrease the vibrational forces, vanes are usually positioned at a certain angle regarding to the flow axis. This study investigates displacement of vanes in three angles of 65, 70 and 75 degrees for a specific geometry using the fluid-solid interaction method. First, the fluid flow is solved using a Finite Volume Method (FVM) solver and the forces exposed by the flow to the vanes are estimated. Next, the displacement of the vanes due to the applied forces is calculated by the Finite Element Method (FEM). Comparison between calculated pressure drop in this study and experimental result show a difference less than 10%. The maximum pressure drop is occurred when the vanes have 65° angle. The most turbulence intensity is obtained at the angle of 75°. Also, according to the frequency estimation, it was observed that with increasing frequency the displacement's amplitude would decrease.

In the present study, the effect of circumferential mode number on natural frequencies of cylindrical shells was investigated numerically and experimentally. Three cylindrical shells with different diameter to length ratios were examined. Different contact type with water were compared using both numerical simulation and experimental tests. The effects of immersion depth, diameter to length ratio, variations of natural frequency with different circumferential mode number were investigated. The reduction of the natural frequencies of the cylindrical shell for the minimum frequency of different circumferential mode number is low, but it increases for higher and lower frequencies, and at the beginning of immersion and at full immersion, the frequency decreases suddenly. Also, as the ratio of diameter to shell length decreases, the frequencies of the low circumferential mode number decrease and the lower value of the natural frequency tends to lower circumferential mode number. At low circumferential mode number, the natural frequencies differ considerably, and with increase of n number, the difference decreases and converges.

Hydrogels are the smart polymeric materials, which undergo large deformation when they are subjected to different physical and chemical stimuli in contact with fluids. These materials can be applied as sensors and actuators for instance in microfluidics in which the fluid-solid interactions have an important effect on its performance. On the other hand, the use of graded materials is also important considering their advantages. In this study, the behavior of a functionally graded temperature sensitive hydrogel micro-valve is investigated through considering the fluid-solid interactions. In this regard, the appropriate numerical tool for finite element modeling of a functionally graded hydrogel micro-valve has been developed that it has been implemented in both non fluid-solid interactions and fluid-solid interactions simulation. The homogeneous cases of the micro-valve have also been considered to distinguish the functionally graded temperature sensitive hydrogel micro-valve effect. The results indicate that the effect of fluid-solid interactions was important and have considerable impact on micro-valve operating parameters particularly its closing temperature and fluid flow rate. Thus, a comprehensive study on hydrogel-based micro-valve has been presented  considering operating parameters such as inlet pressure and cross linking density of hydrogel.

Orbit valves are used dehydration processes of gas. Failure of valves impose cost of repair and maintenance and its experimental tests are more expensive and in many cases are not applicable. Therefore, in this work a three dimensional model of an orbit valve class 900 is created and exported to a CFD solver. Results are exported to a structural analyzer to determine the exerted forces and stresses. Analysis are considered in six position of valve ball. Results show that ball position of 45° is the critical position and probability of failure in this situation is very high. Therefore, results of 45° are valuable to design of parts and choosing appropriate material inside parts.

Turbocharger turbine blade thickness is restricted by blockage and trailing edge losses and it is exposed to damage due to aerodynamic loads. Proper designing of the blade needs to full recognition of loads on the blade. Therefore, the force from the fluid to the blade should be calculated. Although, thickening the blade results to the more resistance to fracture and cracks, but it affects the aero-structural performance of each section of the blade differently. So, turbocharger turbine blades are exposed to pulsating flow which should be considered in thickness distribution selection. This article reports a comprehensive fluid-solid interaction study of the turbine blades with different thickness distribution which could beneficially investigates the effect of each part thickness on the aerostatic efficiency. Leading edge and trailing edge thickness, maximum thickness and its location, trailing edge shape, hub, and tip blade thickness were the variables which their effects were investigated. Using dual turbocharger turbines leads to lower dissipation of kinetic energy of pulsating charge from the engine. In such turbines, each sector of rotor accepts a different charge from upper and lower entries. The flow distribution of every passage is the difference from the others. Therefore, to the evaluation of the flow, modeling of the entire turbine is needed. 3D CFD model in ANSYS CFX for fluid side and an FEA model in ANSYS Static Structural module for the blade structural responses were used then the results were coupled. Validation was performed by reference to experimental data carried out in imperial college London on a dual turbocharger turbine.

In this paper, an active control strategy based on the cylinder forced rotary oscillation is considered to reduce the flow-induced vibration of an elastically mounted two-degree-of-freedom circular cylinder free to vibrate in both transverse and in-line directions. The fluid flow governing equations are two-dimensional incompressible Navier-Stokes model which discretized by means of the finite volume method. The frequency ratio〖 f〗_rot/f_n, and rotation rate α, are two important adjustable parameters which must be selected in such a way that the vortex shedding frequency locked on associated rotational forcing frequency, and the cylinder transverse and in-line vibrations will be suppressed accordingly. Based on comprehensive simulations accomplished in this paper, three different active open-loop control systems is selected in order to effectively reduce the cylinder vibrations for reduced velocities in synchronization region with the following input parameters: (for V_r=5: α=1,f_rot/f_n=1.1), (for V_r=6: α=1,f_rot/f_n=1.3), and (for V_r=7: α=1,f_rot/f_n=1.5). These three control systems are found to decrease the maximum transverse cylinder vibration amplitudes by 88%, 92%, and 92% while the corresponding in-line vibration amplitudes decrease by 93%, 90%, and 82%, respectively.

In this study, considering a real model, numerical simulation of Aorta arch is performed using ANSYS-CFX software. Different aspects such as pulsatile behavior of blood flow and fluid-solid interaction are considered simultaneously in simulation of one and three-layer model for Aorta wall. The results show that the three-layer model leads to stress jumps in boundary of layers the stresses have higher values than one-layer model. For sake of more realistic condition, a hyperelastic model is used for Aorta wall behavior which in comparison to elastic model, the hyperelastic model results to lower stresses. The effect of Aorta arch curvature on the results is examined and it is observed that the von Mises stresses are bigger in Aorta arches with smaller curvature and the maximum value of stresses occurs in ascending part. After investigation of effects of various parameters on wall stresses, the areas with more possible risk of rupture are determined and a proper model for future researches is introduced.

Adipose tissue is a loose connective tissue distributed in two main anatomic depots including subcutaneous and visceral. Since in many pathological condition and diseases associated with adipose tissue alteration, the micro-components of adipose tissue undergoes considerable changes from mechanical characteristics point of view, it is quite vital to present an accurate structural technique for modelling tissue microstructure. Accordingly, this paper presents a structural model based on adipose tissue main components and interaction between them. Adipocytes was considered as a fluidic spheres and extracellular matrix modeled as solid media. The interaction between these two different phases simulated by solving well-known fluid-structure interaction (FSI) problem. In order to obtain the constitutive parameters for ECM, finite element simulation results fitted to experimental uniaxial compression test data. To make a comparison between the performances of different constitutive models, three conventional hyperelastic models were used for describing the mechanical behavior of ECM. The agreement between experimental data and simulation results confirm that the presented technique has a high potential for modeling adipose tissue microstructure both in normal and pathological condition. Considering the accuracy and mathematical complexity, results show that Yeoh hyperelastic model has a better performance than two others. In all three model, results reveals that the stiffness of adipose tissue ECM is ~ (2-3) times higher than that of the adipose tissue.

Unlike HAWT, Darrieus wind turbines is faced with the self-start problem and high fluctuations at output torque. Because of the need for techniques based on meshing and coupling Eulerian fluid equations and the Lagrangian equations for moving rigid body, the calculation of rigid body acceleration and fluctuations torque of VAWT is very complicated and it is a function of the moment of inertia of the turbine. In most studies, regardless of this effect, the angular velocity of turbine is assumed to be fixed. In this study, for calculating the turbine rotational speed and position, the sum of wind-driven aerodynamic forces and external forces caused by friction and generators are calculated and placed into Newton's second law to calculate the acceleration, and integrating it in time steps. The simulation is performed unsteady and dynamic mesh is used for moving the rotor. The results could check the interaction between wind and rigid blades on the in the process of increasing the rotational speed of turbine, and simulate the rotor from the moment of rest until the turbine reaches its final rotational speed. The causes of reduction in torque at low rotational speed is investigated and it has been shown that high dynamic stall and passing high exergy flow into the rotor without interaction with blades results the power reduction. Moment of inertia has significant impact on the frequency and amplitude of rotational velocity, fluctuations of output torque and output power, which is important in mechanical analysis of blades’ fatigue.

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