The main objective of this research is to improve the design and performance of the polyurethane foam-filled thin-walled aluminum Grooved circular tubes using multi-response optimization (MRO) technique. The tubes are shaped with the inner and the outer circular grooves at different positions along the axis. For this aim, several numerical simulations using ABAQUS finite element explicit code are performed to study the energy absorption of these structures. The effects of the grooves distance, tube diameter, grooves depth, foam density, and tube thickness are investigated on the crash worthiness parameters of Grooved circular tubes. Finite-element analysis is performed along the lines defined by design of experiments (DOE) technique at different combinations of the design parameters. The MRO is carried out using the mathematical models obtained from response surface methodology (RSM) for two crashworthiness parameters termed as the specific energy absorption (SEA) and the crushing force efficiency (CFE). Finally, by analyzing all the design criteria including the absorbed energy of tube, the mass of tube, the mean crushing load, and the maximum crushing load, the optimal density of polyurethane foam and geometric parameters were obtained through both multi-objective optimization process and Pareto diagram. A comparison of the obtained results indicates the significance of grooves distance and the inner diameter of the tube as the most influential parameters.

The forced convection heat transfer of turbulent Al2O3-water nanofluid flow inside the Grooved tubes with the different aspect ratio of the rectangular grooves is numerically investigated. The governing equations have been solved using finite volume method (FVM) coupled with SIMPLE algorithm. It is assumed the heat flux is constant on the Grooved walls. The Single-phase approach is applied for the computation of the nanofluid flow. The Nanoparticles volume fraction is in the range of 0-5% and flow Reynolds number is in the range of 10, 000-35, 000. Comparisons between the numerical results and available experimental data show that among different turbulence models, k-e model with enhanced wall treatment gives the better results. The results show that the heat transfer coefficient increases with nanoparticles volume fraction and Reynolds number but it is accompanied by pressure drop augmentation. From the results, it is concluded that the Grooved tubes with Al2O3-water nanofluid flow are thermodynamically advantageous. The Correlations for heat transfer coefficients have been presented for Grooved tubes in different aspect ratios using the numerical results. The optimum geometric ratios in which the entropy generation is minimized are also determined.

This study experimentally evaluated the mixing augmentation of twin tabs mounted along a diameter at the outlet of a convergent-divergent Mach 1.62 circular nozzle. The usefulness of the plain and Grooved tabs is examined at various expansion levels prevailing at nozzle outlet. The tab's performance is assessed through pitot pressure distribution measured along and perpendicular to the jet centerline at different nozzle pressure ratios (NPRs). The shadowgraph technique visualized the shocks and expansion fans in uncontrolled and controlled jets. With the introduction of uncorrugated or plain tabs at the nozzle outlet operating under overexpanded conditions corresponding to NPR 4, the supersonic length (SL) was decreased only by 35.4%. On the other hand, the corrugated or Grooved tabs under similar conditions decreased the SL substantially. Interestingly, the performance of Grooved tabs was best at underexpanded conditions associated with NPR 6, where the SL was reduced by about 88%. The pressure profiles also established the superiority of tabs with Grooved edges in mixing augmentation without introducing any significant asymmetry to the flow field. In addition, the Shadowgraph images also confirmed the weakening of shock strength and reduction of shock-cell length in the case of Grooved tabs at the nozzle exit compared to the plain nozzle.

In this paper, buckling of cylindrical Grooved shells under axial load has been examined by theoretical and experimental methods. The shell is made of USA/API – X42 5L steel standards. This material is one of the most common materials used in gas, oil and petrochemical industries. The effect of spiral grooves on cylindrical shell was analyzed, and the results obtained from the Abaqus software were compared with experimental results. Theoretical and experimental results were in good agreement. Hence, the numerical results can be used as well. It was also found that the number of grooves on the critical buckling load has an important role so that the critical buckling load decreases with an increase in critical load groove.

Boiling is used in processes with high heat transfer rate given the large amount of heat flux involved in the phenomenon. Devising a groove on the surface can improve the bubble formation and increase the heat transfer of the boiling. Accordingly, the pool boiling phenomenon on a horizontal surface is numerically simulated using the Eulerian-Eulerian method in this study. Four surfaces: smooth, with rectangular groove, with triangular groove, and with circular groove are examined to this end. Numerical simulation results are compared with available experimental data. The results indicate that the surfaces with rectangular and circular grooves render approximately 50 and 90% more heat flux than the smooth surface, respectively. However, the surface with a triangular groove rendered approximately 37% less heat flux than the smooth surface.

In this study, the flow field of a new secondary-Grooved cylinder is determined by using particle image velocimetry (PIV) to understand the wake characteristics at different depths of the secondary Grooved cylinders. In order to analyze the wake characteristic behind the secondary Grooved cylinder with different depths, time-averaged streamlines, time-averaged velocity, RMS velocity, Reynolds stress, turbulent kinetic energy, and instantaneous flow structures are employed. The recirculation zone for secondary Grooved cylinders with different depths decreases when compared to the smooth cylinder, the peak magnitudes of flow velocity fluctuation intensity and transverse velocity fluctuation intensity for secondary Grooved cylinders with different depths are reduced and the locations appear delayed. Furthermore, in contrast to the smooth cylinder, the secondary Grooved cylinders with different depths' Reynolds stress and turbulent kinetic energy are increased by the wake flow, and the transient large-scale vortex is split into several smaller-scale vortices behind the secondary Grooved cylinders. The results obtained for the above flow structure are more significant when h/D = 0. 05 for the secondary Grooved cylinder.

Providing adequate skid resistance is one of the most important issues in the construction of concrete pavements and due to the lack of sufficient friction, smooth concrete pavements can only be used in the places where skid resistance doesn't matter so much; such as parking lots and warehouses. Although there is no comprehensive instruction for texturing on concrete pavements, methods such as grooving, burlap or broom dragging, and exposing the aggregates are used to texture the concrete pavements.In this study, the method of grooving is studied using British pendulum sand patch tests.Therefore, grooves in three different center to center spacings(12.7 mm, 19 mm, 25.4 mm), three different widths (2.5 mm, 3.2 mm, 3.8 mm) and three different directions(transverse, diagonal and longitudinal) were created on concrete specimens.The results of this study indicate that increasing the spacing of the grooves or decreasing the width of them, decreases the depth of the texture.The friction value in every three direction of the grooving decreases by increasing the spacing between the grooves; while increasing the widths of the grooves leads to an increase in the friction values at first; but then the value decreases in the wider grooves.The results show that the transverse grooves lead to the highest skid resistance.

Hyper-tubes consisting of hyper-cubes of n -dimensions were designed and formulas for substructures of vary dimensions established.

In this article, turbulent flow heat transfer in the air gap between rotor and stator of a generator under nonhomogenous heat flux is studied experimentally. The rotor consists of four symmetrical triangular grooves. The stator surface is smooth and does not include any grooves. The relative heat flux between the rotor and the stator is 1 to 3. Temperature and heat flux are measured locally at three axial and two angular positions of inner and outer surface. The pressure drop of air flow through the air gap is also measured. In this work, the axial Reynolds number and rotational velocity of the rotor ranges are 4000<Rez<30000 and 300rpm<w<1500rpm, respectively. The results indicate that increasing the rotational velocity causes the rotor and stator heat transfer coefficient to increase considerablly and the respective value to the rotor is higher than that to the stator. In addition, the rotational velocity causes the air flow to be developed sooner.

To obtain a higher heat transfer in the low Reynolds number flows, wavy channels are often employed in myriad engineering applications. In this study, the geometry of grooves shapes is parameterized by means of four angles. By changing these parameters new geometries are generated and numerical simulations are carried out for internal fully developed flow and heat transfer. Results are compared with those of rectangular Grooved channel. Two different Prandtl numbers, i. e. 0. 7 and 5, were investigated while Reynolds number varies from 50 to 300. An element-based finite volume method (EBFVM) is used to discretize the governing equations. Results reveal that that both heat transfer performance and average Nusselt number of rectangular Grooved channel were higher than those of other geometries.