Let G be a simple connected graph. In this paper, Szeged dimension and PIv dimension of graph G are introduced. It is proved that if G is a graph of Szeged dimension 1 then line graph of G is 2-connected. Trees of Szeged dimension 1 are characterized. The Szeged dimension and PIv dimension of five composite graphs: sum, corona, composition, disjunction and symmetric difference with strongly regular components are computed. Also explicit formulas of Szeged and PIv indices for these composite graphs are obtained.

Thermosyphons are devices used to transfer heat from a hot to a cold source benefiting the effect of gravity.They consist of three main parts, namely, evaporator, condenser and adiabatic section. Working fluid absorbs heat from the heat source and delivers it to the condenser section and releases it into the environment. Thermosyphones are able to transfer heat between the heat sources and sinks. Due to the high latent heat of the working fluid, thermosyphones can transfer huge amounts of energy.Therefore, they are considered one of the best heat transfer devices. They are widely used in various industrial fields, such as in solar systems, microelectronic devices, CPU cooling and air conditioning. Most researchers in this field focus only on heat transfer characteristics, and, due to practical considerations, rarely consider their hydrodynamic specifications. Indeed, the hydrodynamic characteristics of thermosyphones consid Thermosyphons are devices used to transfer heat from a hot to a cold source benefiting the effect of gravity.They consist of three main parts, namely, evaporator, condenser and adiabatic section. Working uid absorbs heat from the heat source and delivers it to the condenser section and releases it into the environment. Thermosyphones are able to transfer heat between the heat sources and sinks. Due to the high latent heat of the working fluid, thermosyphones can transfer huge amounts of energy.Therefore, they are considered one of the best heat transfer devices. They are widely used in various industrial fields, such as in solar systems, microelectronic devices, CPU cooling and air conditioning. Most researchers in this field focus only on heat transfer characteristics, and, due to practical considerations, rarely consider their hydrodynamic specifications. Indeed, the hydrodynamic characteristics of thermosyphones considerably affect their performance. In this paper, the velocity profile in the liquid phase is determined via a particle image velocimetry technique (PIV). For this purpose, a typical thermosyphon has been designed and constructed with transparent up riser and down-comer sections. In this study, a circular thermosyphon is analyzed and water is used as a working fluid in the circular thermosyphon. At the beginning, the velocity field of the liquid phase is detected in the transparent thermosyphon using a high speed camera and an image processing technique. Subsequently, these pictures are used to generate the velocity profiles and are combined with theoretical analyses to evaluate the performance of the thermosyphon. The results are compared with numerical investigations and show good consistency. The results indicate that the particle image velocimetry (PIV) truly determines the hydrodynamic and thermal characteristics of the thermosyphones. Moreover, in this study, the effect of input heat and the inclination angle of the thermosyphon are investigated numerically. It has been shown that the maximum efficiency of thermosyphon is in a horizontal position.

The proper and quantitative recognition of the scale of turbulence in regard to issues such as sediment transport is of major importance. Different experimental techniques can be used to determining the scale of turbulence, but the accuracy of these techniques is open to question. In this paper, after a review of the Taylor method, the restrictions and advantages of velocity measurement techniques such as hot wire anemometry (HWA), laser doppler velocimetry (LDV) and particle image velocimetry (PIV) are described.Correlation coefficients were applied to determine the scale of turbulence using these techniques. The results showed that the main restrictions of the HWA technique were its intrusiveness and the sensitivity of the sensor. The LDV technique was restricted to measuring correlation coefficients in small distances and for just one velocity component. The results showed that the PIV technique has restrictions in its framing rate, saving image, image resolution and laser pulsing frequencies. However, considering the large spatial domain of PIV and its non-intrusive measurements and especially the continuous development of its capabilities, PIV is an appropriate technique for determination of the scale of the flow of turbulence.

This paper introduces a new type of flame holder. Flow field is investigated, using PIV measurements in cold flow regime. The experiments on two types of V-shape flame holder: one with smooth edges and the other with wavy edges. The instantaneous velocity fields, Strouhal number, average velocity, vorticity, and recirculation zone length were among the parameters affected by the flame holder geometry. In this work, we examined the influence of these characteristics. Complex structure and unsteadiness of the flow was obtained with high accuracy. The results indicate an increase in length and width of the recirculation zone when using the wavy edges instead of smooth edges. For both geometries, a symmetrical flow structure was observed behind the flame holder. Also, higher static pressure drop was detected behind the flame holder for geometry with wavy edges.

The hydraulic jump on negative steps forms in stilling basins. In this paper the hydraulic and hydrodynamic behavior of these flows were studied. The experiments were performed in a channel with length: 6m depth: 0.5m and width: 0.47m. The step heights were 2.5, 4 and 7cm. The varied parameters in hydraulic study were 1. Froud number 2. The ratio of secondary depth to initial depth 3. The ratio of the step height to initial depth. By changing the initial velocity of hydraulic jump, step height and tailwater depth different kinds of hydraulic jumps were formed. For estimating the hydraulic jump shapes different curves were derived. Study about the pressure correction coefficient were done. In hydrodynamic study PIV apparatus was used. This apparatus can measure the velocities in confined surface. In hydrodynamic study the mean velocities and turbulent parameters were investigated. Because of limitations of PIV, the hydrodynamic studies were done only for two different kind of wavy hydraulic jumps and an A jump.

One of the essential areas of the study of transport in porous medium is the flow phenomena at the onset of inertia. While this area has attracted considerable research interest, many fundamental questions remain. Such questions relate to things such as the nature of the multi-dimensional velocities of the flow, the evolution of inertia, the differences in flow phenomena at various complexity of porous media, and the best constitutive equation for the flow. To resolve some of these questions, the present research program was designed to experimentally investigate pressure-driven flow through two-and three-dimensional porous media at the onset of inertia. Specifically, the goals in view were to obtain velocity data and pressure measurements, apply the benchmark experimental data to study the evolution of inertia, distinguish differences in such evolution with respect to the parameters of the porous media, and to establish the constitutive equation that best describes the porous media flow when inertia sets in. What particularly sets this work apart, is the use of particle image velocimetry (PIV) – an experimental technique that captures multi-dimensional flow quantities, as opposed to mere flow rates. Using PIV then, detailed velocity measurements were conducted for flows through model porous media of solid volume fraction 6%, 12%, and 22%. The velocities were spatially averaged to obtain average streamwise and transverse components. In addition to the velocity measurements, differential pressure measurements were obtained using pressure-measurement gauges and transducers. The pressure and velocity data sets were then statistically analyzed and presented to provide a complete set of experimental data to characterize the flow through the model porous media. The results show that the velocity flow domain is dictated by the streamwise velocities, which are at least an order of magnitude greater than the transverse components. Furthermore, pressure drag was found to increase with compactness and complexity of the porous media. While inertia increases exponentially from particle Reynolds number ~ 1 – 3 onwards, it is apparently subdued by the form drag that tends to dominate the flow through complex media. Overall, the flow at the onset of inertia is best described by a power law. These results provide insights that are applicable to flows such as those near well bores and fractures where seepage velocities are relatively high.

In this paper, the flow field between two straight groynes in shallow wide open channel has been measured using Particle Image Velocimetry method. Groynes with 25cm length, 5cm width and 7cm height with two aspect ratios (l) of 1 and 2 have been located in the fully developed zone of a 18m length flume and velocity measurements carried out in order to study the circulating flow, structure of the mixing layer and downstream separation zone. Surface Particle Image Velocimetry was conducted using two Procilica GE1910 CCD cameras with 37 Hz measuring frequency. Images resolution was 90*1660 pixeles. Image processing was performed using GPIV software and Westerweel, 2005 and Brevis, 2009 methods were used for filtering of the measured velocity fields. Matlab programs were developed for the post processing of the measured data. Results are presented in forms of time averaged values, turbulence intensities and the Reynolds stresses at the various zones of the groyne field. Results showed that due to the flow shallowness, most of the turbulent structures are two dimensional. Development of a back flow from downstream zone to the groyne field enhances the complexity of the mixing layer and mas exchange phenomenon compared to the groyne series configuration. In the l=1 case, a fully developed gyre forms inside of the groyne field. The circulation zone is connected to the mixing layer at the head of the upstream groyne. By increasing the distance between the groynes, i.e., for the l=2 case, another circulation zone forms inside of the mixing layer. Consequently the circulation zone inside of the groyne field is depressed in the transverse direction. In the both cases a single gyre forms inside of the groyne field. While, the previous works showed that in the groyne series case, by increasing the aspect ratio, number of the gyres between groynes increases. Furthermore, unlike to the two groynes case, gryres rotate in the clockwise direction.In two groyne case, the rotational energy is fed from the vorticity of the back flow to the circulation zone in the groyne field, while in the groyne series case, the momentum transfer between the free flow and the dead zone in the groyne field is responsible for the formation of multiple gyres inside of the groyne field. Two groynes field has complex dynamic flow features and it is not a suitable choice for modification of the river alignment or the bank stabilizing projects. On the other hand, they move the high velocity zone to the channel center and they could be used as protection measures for the river structures like bridge abutments.The mixing layer of two groynes case is fully dynamic and it can deeply penetrate into the groyne field. While, in the groyne series case, exchange processes between dead zones and main stream are governed by large coherent two-dimensional structures which are generated at the head of the upstream groyne. Consequently, in terms of the environmental issues, the retention time of the trapped pollutants in a two groynes field will be shorter than the groyne series case.

In this research, failure mechanism, soil deformation and effect of reinforcement below a strip foundation were studied using physical modeling and PIV method. For this purpose, a comprehensive set of tests were undertaken on dense and loose sands and different geosynthetic materials such as geotextile and geogrid for soil reinforcing. In each step of loading, digital image of deformed soil was captured and image processing was applied with GeoPIV software. The experimental results showed that using of geogrid and geotextile leading to increase bearing capacity considerably, reduce settlement and change the failure mechanism of sand. The test results showed also that geogrid has an effective performance in comparison with geotextile in sand at the range of small strains.