The current manuscript presents the validation of Smoothed Particle Hydrodynamics (SPH) techniques for wave generation by UNDERWATER EXPLOSION, utilizing the so-called Duals Physics numerical model. This numerical method is used to analyze generated waves which are initiated by man-made or natural EXPLOSIONs below free surface level of sea. In spite of the modeling limitations (e.g. absence of open boundary conditions), reasonable agreement is accomplished with predictions of the existing formula as well as experimental results. This proved that SPH techniques such as incorporated in Duals Physics are becoming a suitable alternative to existing classical approaches to this particular water waves problem. It is also provided an inherently more accurate computational for the prediction of wave characteristics generated by UNDERWATER EXPLOSIONs.

In this research behavior of bubble due to under water EXPLOSION and it's effects on ship structure have been studied. For determination of these effects field equations must be derived and solved them by mathematical simulation. Mathematical model is corn in follow, it show physical rules on impression of bubble oscillation on body ship. This model is solved by combination of Euler method, 5 steps Adams-Beshforse method and 4 step Adams-Moltone method for explaining the response of ship structure due to oscillation bubble. In order to agreement of solution way, stress-strain curves that obtained in this paper, is compared with experimental results. Also these results compared with FEMA results. Ship structure is modeled in ANSYS software in free beam form with variable mass and stiffness elements. Internal ship's equipments and buoyancy are modeled by local mass and spring.The effect of EXPLOSION depth and explosive mass on stress in ship structure is studied. These result show when EXPLOSION depth is increased, stress is decreased and when explosive mass is increased, stress is increased.  

In this paper, a numerical scheme is proposed for the multi-fluid compressible flows. This method is applied to the problem of UNDERWATER EXPLOSION. The proposed scheme is basically the extension of Godunov method in gas dynamic problems to the multi-fluid environments and is second-order accurate in space. In this method, also, the problem of artificial mixing of two different phases on Eulerian grids is prevented by a front tracking technique. The numerical results of this study are in very good agreement with previous numerical and experimental results.

UNDERWATER EXPLOSION is a common phenomenon to be considered for marine and coastal structures. Although it is not wise to design such structures based on EXPLOSION loads, but having studied the EXPLOSION wave and its demotic effects, location and geometries of these structures can be improved. In this study after introducing UNDERWATER EXPLOSION mechanism a summary of the numerical methods used for propagation of EXPLOSION waves in water is introduced and finally a preferable method is proposed for modeling the phenomenon. Based on such considerations numerical results using multipurpose commercial codes are successfully compared with empirical relations.

In the present paper the compressible flow of the UNDERWATER EXPLOSION has been simulated using One-fluid method along with the Eulerian-Lagrangian ALE method. Besides, the exact Riemann solver and an appropriate equation of state which is consistent with the thermodynamic behavior of water in UNDERWATER EXPLOSION, is employed.The two dimensional UNDERWATER EXPLOSION problem near a flat plate is modeled. In order to increase the accuracy of the method for simulating the wave front, the adaptive grid is used. The simulated UNDERWATER EXPLOSION results agreed well with other similar numerical simulations. The numerical results indicate the capability of the present study in simulating the physics of UNDERWATER EXPLOSION and modeling the fluctuations of explosive bubble and also predicting the creation and collapse of the caviation zone.

Behavior of blast wave in UNDERWATER EXPLOSION is of interest to metal forming community and ship designers. UNDERWATER detonation is, also a potential hazard to the water intakes or a plant spent fuel pool. In this paper, some techniques for calculating free-field blast parameters such as pressure and impulse in UNDERWATER EXPLOSION and prediction of bubble pulsation parameters are presented and they will be compared by experimental results of UNDERWATER detonation of Hexogen explosive charge. The details of pressure pulse curves generated by detonation of Hexogen in several standoff distances are obtained, that by using scaling laws, they can be used in analysis of practical UNDERWATER detonations. Finally, the equivalent mass of Hexogen charge relative to TNT in UNDERWATER EXPLOSION is calculated.

Studying the responses of dams to EXPLOSION-induced loads and evaluating their overall safety under such loads is highly significant regarding the strategic importance of dams. The present study investigates TNT-induced wave effects on the Karun-4 Dam in Iran. For this purpose, dynamic analyses were carried out on the dam reservoir and foundation system via the finite element method (FEM) in ABAQUS. The CONWEP theory allows the imposition of pressure loading caused by an EXPLOSION in the air. The reservoir was considered empty, and then three different heights of 225, 115, and 5 m were analyzed. The failure explosive weights of the three heights were calculated by trial and error. Analyses were performed with 1000, 1200, and 1300 kg of TNT for the height of 225 m, 1900, 1950, and 2000 kg of TNT for the height of 115, and 1800, 1900, and 2000 kg of TNT for the height of 5 m. It was observed that the dam failed at loads of 1300, 2000, and 2000 kg of TNT when the EXPLOSION occurred at 225, 115, and 5 m, respectively. The analyses were performed based on these loads. The results indicated that the reservoir water level had a negligible effect on the arch dam's failure blast load. Moreover, analysis results of the dam-reservoir-foundation system in filled-up and empty reservoir cases suggest that the failure explosive loads of filled-up and empty reservoir dams do not significantly differ, and the failure explosive load of the filled-up case is slightly lower than that of the empty case. For example, at an EXPLOSION height of 225 m, the failure load of the filled-up reservoir case was derived to be 1500 kg of TNT, while that of the empty reservoir case was obtained to be 1300 kg of TNT.

An accurate and safer analysis for structure is possible if we can identify factors in the analysis more accurately.One of the important factors in the analysis is the identification the kind and intensity of structural loading. Among the types of loading, especially dynamic loads and impact loads resulting from the EXPLOSION, is far more complicated and difficult to determine. According to lab EXPLOSION modeling problems, using numerical modeling to analyze these phenomena can be reasonable. Uses grid methods like Finite element method caused a numerical error due to intense deformation and high velocity of blast. In this paper, UNDERWATER EXPLOSION was modeled and programmed with numerical mesh-less method, Smooth Particle Hydrodynamics (SPH), using Fortran programming language and EXPLOSION pressure and water level changes in the blast were studied. Finally the solving problem is compared with empirical relation. The results of this model are very similar to empirical relationship. This program can be used for UNDERWATER EXPLOSIONs modeling and the results can be used to determine pressures and impacts on marine structures.

The aim of this paper is to develop a numerical procedure for simulating UNDERWATER EXPLOSION phenomena with a simplified mathematical and two fluid model. The two fluid Kapila five equation model is selected as the governing equations and the ideal gas and Stiffened gas equations of state (SG-EOS) are used to obtain pressure in the gas bubble and the surrounding water zone, respectively. The modified Schmidt EOS is used to simulate the cavitation regions with low pressure. A Godunov numerical method and HLLC Reiman solver is extended for Kapila two fluid model. The numerical results of the present method and comparing them with available experimental results, verify that the proposed method has good capability of predicting complex physics involved in a spherical UNDERWATER EXPLOSION and its interaction with free surface. The method also shows a very good performance with no spurious oscillation in cavitation zone simulation in two-dimensional problems.