Nowadays, the fundamental role of having a purpose for life in physical and mental health has been confirmed. According to victor frankl, presence of a purpose in life gives life a meaning and increases resilience against pains and traumas. The importance of the purpose in life construct reveals the need for a reliable and valid tool to measure it. Crumbaugh and Maholick's purpose in life questionnaire is the first and one of the most applied tools for the assessment of life's purposefulness. The aim of this research is to determine the factor structure of purpose in life questionnaire. The questionnaire was administered on 206 students who were selected through random stratified sampling at Ferdowsi University of Mashhad. Exploratory factor analysis showed that there are two factors "comprehension" and "purpose" and this finding were confirmed by confirmatory factor analysis. Altogether results of this research showed factor validity of the purpose in life questionnaire with a two factor pattern

The work presented here comes within a research program dealing with Vortex detection in the impingement region of a planar jet. In this study, experiments have been performed for a submerged turbulent water slot jet impinging normally on a flat plate, and an emphasis was put on the flow field characteristics. For this purpose, particle image velocimetry (PIV) have been employed. A comprehensive fluid mechanical data includes instantaneous and mean flow field, variance of normal and cross velocity fluctuations have been presented. The present work is also concerned with the flow structure in the impingement region where the transfers (heat/mass) occur. An attempt has been made to understand the flow structure by employing the Vortex detection criteria on the instantaneous velocity vector field. Accordingly, the PIV measurements were carried out for four different Reynolds numbers: 3000, 6000, 11000 and 16000, and at three different planes: a plane parallel to the impingement plate, transverse plane of the jet and a plane perpendicular to the jet. A method of filtration, based on proper orthogonal decomposition (POD) technique was applied first to the instantaneous velocity and filtered velocity database is then used for Vortex detection. Further, the results about the size, shape, spatial distribution and energy content of the detected vortices have been provided.

In this manuscript, the Vortex generated by the main frequency excitation of the shedding Vortex at various attack angles is investigated by employing the synthetic jet control technique. We also analyzed the impact of the Vortex structure on the fled flow around the wing and the spectral characteristics corresponding to the Vortex. The dominant frequency and harmonic frequency corresponding to the wave rule of the shedding Vortex at various attack angles without the absence of a synthetic jet are selected as the synthetic jet excitation frequency. The results indicate that under the excitation of fixed frequency synthetic jet, the shape of the shedding Vortex in the flow field turns correspondingly. Compared with the flow field without jet excitation, it is found that the field with the jet at most attack angles is stable in 2S (Single) mode, and the flow field at a small attack angle is stable in a chaotic state. The angle of attack with a chaotic state is delayed by adding a jet, which makes the curves and corresponding spectral characteristics more orderly. At a defined attack angle, the combined frequency synthetic jet will cause the lift coefficient to fluctuate regularly. At this time, the multiple small-scale Vortex structures lead to lift reduction.

Vortex drop shaft (Vortex structure) is used in sewage and drainage systems to transfer fluid from surface conduit to deep underground tunnels. During the plunge, large volume of air is entrained into the water and then released of the drop shaft downstream. In the current research, an experimental model, made of Plexiglas segments, was set up to investigate hydraulic performance of Vortex structure. Dimensional analysis results illustrated that ratio of sump depth to shaft diameter (Hs/D), ratio of drop total height to shaft diameter (L/D), and Froude number (Fr) were considered effective variables on relative air discharge (l=Qa/Q). The ability of the full factorial method (FFM), to describe this structure’ s hydraulic characteristics, was validated using experimental data. The results indicated that the relative air discharge changed from 0. 048 to 0. 278 and increased with an increase in Fr, L/D and Hs/D factors. With respect to the maximum velocity of air outflow from the structure of the air vent pipes (with the same diameter Da), located between the 4Da and 9Da from the axis of the vertical shaft, this range is recommended for installation of air vent pipes. Furthermore, a regressionbased-equation in the form of a quadratic polynomial as a function of Hs/D, L/D and Fr was proposed to estimate relative air discharge (l).

With rapid rise in development of urban districts, a ferocious demand for water-collecting urban sewer systems is inevitable. In fact, flexible sewer collecting systems and drainage systems should be developed for controlling sewage and runoff, respectively. In the case of underground, conducting water flow properly through high vertical distances needs reliable criteria design for dissipating flow energy. Vortex structure is taken into account as one of the economical infrastructures which can be used to eradicate destructive impacts of inflow over a drop with invert elevation. In the current investigation, a physical model, made of Plexiglas segments, was set up to study hydraulic performance of Vortex drop structure in terms of flow energy dissipation efficiency (FEDE). 144 experiments were conducted and analyzed by means of full factorial method (FFM). Results of dimensional analysis demonstrated that Froude number (Fr), ratio of drop total height to shaft diameter (L/D), and ratio of sump depth to shaft diameter (Hs/D) were considered effective variables on the FEDE. Hence, a regression based equation in form of a quadratic polynomial was proposed to estimate FEDE variable. Experiments aims were to investigate simultaneous effects of approach flow Fr, L/D, Hs/D on the FEDE. Results of experiments indicated that FEDE variable had downward trends with an increase in Fr variable and additionally, FEDE has gone through upward trends with an increase of L/D and Hs/D ratios. Increase in ⁄ , which causes remarkable effect of wall friction on Vortex flow, leads to increase in FEDE in the structure. Moreover, observations showed that decrease in inlet discharge for smaller Froude number results in more rotations of Vortex flow in vertical shaft than flow with larger discharges for larger Froude number. This causes reduction of FEDE due to increase in inlet discharge. In addition, shown that in the structures with smaller ⁄ ( ⁄ ), the reduction effect of on the FEDE is more. With respect to positive effects of sump depth range ( ⁄ ) on FEDE and flow patterns observed in the entrance outlet tunnel, range ( ⁄ ) can be replaced by ⁄ range (0. 7-1) proposed Zhao et al. [11]. In addition, the results showed that the interaction of and Hs/D on the FEDE in the structure is not significant. For Q between 9. 7 and 27. 1 l/s, formation of hydraulic jump in tangential inlet was not occurred and flow was drained freely to drop shaft. Additionally, water surface in tangential inlet was lower than that of approach channel. In the outlet part of Vortex structure, flow hitting the baffle leads to relatively significant increase in flow elevation top of the baffle in comparisons with other parts. Moreover, for constant values of Q and Hs/D ratio, flow elevation over the baffle has increased with an increase in L/D ratio, while for constant values of Q and L/D ratio, flow elevation has plummeted with an increase in Hs/D. Observations of experiments indicated that baffle-hitting flow accelerated without existence of sump at the base of drop shaft. Then caused to detaching flow and consequently occurrence of cavitation increased.

Analyzing the Vortex-induced vibration of a slender marine structure with length to diameter ratio up to 200 is the objective of this study. This slender is free to move in both in-line and cross flow directions and immersed completely in water. Three different types of shear currents pass on it and cause to vibrate slender in different forms. Nowadays, these vibrations are very important for designers. In this study, 3D Finite difference method has been used to solve cable governing equations in a long slender with two hanged ends. The hydrodynamic forces, in the direction of in-line and cross-flow created by Vortex shedding are simultaneously considered based on Morison equation. In a specified range of Reynolds number, the flow is in-line direction, but the results show riser oscillation in both in-line and cross flow directions. The results showed a good agreement with other researches in VIV with constant flow on it. Then non-uniform flows with profiles in real ocean currents were selected as inputs of this study. The results showed that small variations in velocity profiles and quantities can create significant differences in riser behavior.

One of the basic needs in urban wastewater and drainage systems is the connection of shallow ducts to deep underground tunnels. This connection is usually made through a Vortex drop structure. In order to form a Vortex flow, in addition to preventing the fluid from falling, a significant part of its energy is lost due to the friction of the walls. In the present study, by constructing a physical model, the residual energy head in the structure (ratio of specific energy at the output (E2) to specific energy at the input of the structure, (E1)) has been studied. Using dimensional analysis of dimensionless factors of Froude number (Fr), the ratio of total fall height to shaft diameter (LWD) and the ratio of sump depth to shaft diameter (Hs WD) were determined as factors affecting the residual energy head in the structure. Using experimental observations, the accuracy and capability of the full factorial method to describe the residual flow energy in the structure were evaluated. The results showed that the residual energy head for the Froude number corresponding to the design flow discharge at Fr=2. 18 is closest to the limit value of 1. On the other hand, for all L/D operating levels, the residual energy head values are close to 1. Moreover, the smallest difference between the values of the residual energy head and the limit value was 1 for Hs/D values between 1 and 2, indicating suitable range for the practical purpose. In addition, a polynomial equation as a function of Fr, LWD and Hs WD was expressed to accurately estimate the residual energy head in the Vortex, drop structure using regression analysis.

Immersed boundary method is a novel and efficient tool for solving fluid-structure interaction problems. One of important fluid-structure interaction problems is Vortex-induced vibrations of cylinders. In this study, we want to introduce immersed boundary method. Philosophy, advantages, disadvantages and applications of the method will be presented. Because of wide range of applications of this method and for not losing focus, we shall limit our study only to Vortex-induced vibrations. Next, details of governing equations of immersed boundary method and their discretization will be introduced. Iterative immersed boundary algorithm which has been used for Vortex-induced vibrations before, will be used to solve governing equations. Finally, implementation and coding requirements will be discussed. This paper is organized in a way so readers can obtain a comprehensive understanding of the method behavior in fluid-structure interaction problems, especially Vortex-induced vibrations. Considering the benefits of immersed boundary method, it has the potential to become the main method for analyzing fluid-structure interaction problems. These benefits are considerable enough that makes the implementation of the method justifiable.

Introduction: Vortex induced vibration is a well-known phenomenon in the engineering applications involving the fluid/structure interaction. Especially, it has been observed in various ocean engineering applications such as offshore risers, deep water bridge piers and oil pipelines. In the flow around bluff bodies such as marine risers, in a specific range of Reynolds numbers, the asymmetric Vortex shedding at the bluff body wake results in periodic hydrodynamic forces on the riser and consequently the Vortex-induced-vibration. When the Vortex shedding frequency is close to the natural frequency of the structure, the cylinder tends to dramatically vibrates in transverse direction which is commonly termed as the "lock-in" phenomenon. Since Vortex induced vibration is one of the most important causes of fatigue damage and structural instability in marine risers, exploring efficient ways to reduce or suppress Vortex induced vibrations, has attracted the attention of many ocean engineering researchers. In the present study, two-way fluid/structure interaction simulation of the Vortex induced vibration of the circular and truncated cylinders are conducted. For this purpose, laminar flow around an elastically supported two degree of freedom cylinder (circular or truncated), which can freely vibrate in stream-wise and transverse directions, is considered. Methodology: To solve the governing equations of two-dimensional, unsteady and incompressible flow over circular and truncated cylinders, a finite volume technique is employed. Moreover, the rigid body motion equations in stream-wise and transverse directions are incorporated into the computational fluid dynamics solver to treat the coupling which exists between the fluid flow and cylinder movement. To calculate the rigid body motion of cylinder and treat the fluid-cylinder interaction, a user-defined function is used. In every time step, the temporal variation of hydrodynamic forces (i. e., lift and drag) determined by solving the mass and momentum equations, which are employed as the source terms in rigid body motion equations to compute the velocity and displacement of cylinders. Fluidstructure interaction is handled using the Fluent's moving deforming mesh feature which deforms and remeshes cells during transverse and streamwise motions of the cylinders. The pressure-based solver with first-order implicit unsteady formulation is employed to solve the discretized continuity and momentum equations. The coupling between pressure and velocity fields are handled by using computationally efficient fractional step method along with the non-iterative time-advancement algorithm for time matching strategy in the computational fluid dynamics solver. To solve the governing equation for the velocity fields, one needs suitable boundary conditions at the inlet, outlet, lower and upper boundaries, and on the surface of cylinders. A uniform profile of free-stream velocity is used at the inlet. At the outlet, the downstream boundary is located far from the cylinders such that the streamwise gradients for the velocity vectors could safely be set equal to zero. Along the upper and lower boundaries, the y-component velocity is considered to be zero while for the x-component velocity, the gradient in the y-direction is set equal to zero. At the cylinder’ walls, the no-slip condition is imposed on both velocity components. Results and discussion: In order to validate the numerical method used in the study of fluidstructure interaction, the results for the transverse oscillations of the circular cylinder and truncated one (with truncation angle of 45 degrees) at different Reynolds numbers are compared with the results of Kumar et al. (2018). It is noteworthy that the obtained results in the present study are in good agreement with those of Kumar et al. (2018) and the numerical model accurately predicts the maximum amplitude of transverse vibration and the width of the lock-in region. Moreover, the influence of the truncation angle (behind the cylinder) on the vibration suppression of truncated cylinders is evaluated. The results show that as the Reynolds number increases from 80 to 85, the vibration of the truncated cylinders enters the lock-in region and experiences a sharp jump in their transverse displacement. Also, in this region, the truncation angle does not have a significant effect on the transverse vibrations of the cylinders and merely reduces their in-line vibration. However, changing the structural design of the cylinder (making a truncation at the back of the cylinder) has a substantial effect on the vibration reduction in the right half of the synchronization region. At Re = 100 (Reynolds number corresponding to the lock-out region), when the truncation angle increases from zero to 60 degrees, the transverse vibration of the cylinder is reduced by about 66%. Conclusion: In summary, it is concluded that the significant difference in the oscillation amplitude of the circular and truncated cylinders is in the right half of the lock-in region. When the truncation angle increases, the width of the lock-in region decreases.