The technology of Autonomous Underwater Vehicles (AUVs) is developing in two main directions focusing on improving autonomy and improving construction, especially driving and power supply systems. The new Biomimetic Underwater Vehicles (BUVs) are equipped with the innovative, energy efficient driving system consisting of artificial fins. Because these driving systems are not well developed yet, there are great possibilities to optimize them, e.g. in the field of materials. The article provides an analysis of the propulsion force of the fin as a function of the characteristics of the material from which it is made. The parameters of different materials were used for the fin design and their comparison. The material used in our research was tested in a laboratory to determine the Young’s modulus. For simplicity, the same fin geometry (the length and the height) was used for each type of fin. The Euler–Bernoulli beam theory was applied for estimation of the fluid–structure interaction. This article presents the laboratory test stand and the results of the experiments. The laboratory water tunnel was equipped with specialized sensors for force measurements and fluid–structure interaction analysis. The fin deflection is mathematically described, and the relationship between fin flexibility and the generated driving force is discussed.

This article presents the analysis of fi n drag force in a Biomimetic Underwater Vehicle (BUV). To carry out numerical simulations Incompressible Computational Fluid Dynamics (ICFD) solver was used. The simulation model was verifi ed in the designed laboratory test stand. The laboratory test stand was equipped with specialized sensors for force measurements and control of fl uid velocity. An average value of fl uid velocity in the water tunnel was measured by specialized high accuracy ultrasonic fl owmeter. A vision system was used for analysis of laminar and turbulent fl ows in the fl uid structure interaction area. The research of fl uid-structure interaction phenomena was depicted using dimensional analysis. Sažetak U radu se daje analiza sile otpora biomimetičkog podvodnog vozila (BUV). Za provođenje numeričkih simulacija koristio se program Računalna dinamika fl uida (ICFD). Simulacijski model provjeren je u posebno izrađenom laboratoriju. Laboratorij je opremljen specijaliziranim senzorima za mjerenje sile i kontrole brzine fl uida. Prosječna vrijednost brzine fl uida u vodenom tunelu izmjerena je specijaliziranim i vrlo preciznim ultrasoničnim uređajem za mjerenje brzine strujanja. Sustav promatranja koristio se za analizu laminarnih i turbulencijskih strujanja u području interakcije u strukturi fl uida. Istraživanje fenomena interakcije u strukturi fl uida provedeno je uporabom dimenzionalne analize. KEY WORDS artifi cial fi sh fl uid structure interaction (FSI) computational fl uid dynamics (CFD) biomimetic underwater vehicle KLJUČNE RIJEČI umjetna riba interakcija u strukturi fl uida (FSI) računalna dinamika fl uida (CFD) biomimetičko podvodno vozilo

In this paper, a hydroacoustic system designed for a biomimetic underwater vehicle (BUV) is presented. The Biomimetic Underwater Vehicle No. 2 (BUV2) is a next-generation BUV built within the ambit of SABUVIS, a European Defense Agency project (category B). Our main efforts were devoted to designing the system so that it will avoid collisions with vessels with low-speed propellers, e.g., submarines. Verification measurements were taken in a lake using a propeller-driven pontoon with a spectrum similar to that produced by a submarine propulsion system. Here, we describe the hydroacoustic signal used, with careful consideration of the filter and method of estimation for the bearings of the moving obstacle. Two algorithms for passive obstacle detection were used, and the results are discussed herein.

The article presents the calculations of Cooling Skid units used on oil rigs required by the specific provisions of the classification society American Bureau of Shipping (ABS). Stringent requirements for equipment intended for offshore drilling research relates to the strength of the environmental loads such as wind loads and strength check points in towing and lifting hooks. The article describes how the simulation calculations are carried out to meet the criteria set for by the classification society American Bureau of Shipping (ABS).

Numerical simulations of air blast loading in the near-field acting on the ground have been performed. A simplified blast model based on empirical blast loading data representing spherical and hemispherical explosive shapes has been simulated. Conwep is an implementation of the empirical blast models presented by Kingery and Bulmash, which is also implemented in the commercial code LS-DYNA based on work done by Rahnders-Pehrson and Bannister. This makes it possible to simulate blast loads acting on structures representing spherical and hemispherical explosive shapes of TNT with reasonable computational effort as an alternative to the SPH and Eulerian model. The CPU time for the simplified blast model is however considerably shorter and may still be useful in time consuming concept studies. Reasonable numerical results using reasonable model sizes can be achieved not only for modelling near-field explosions in air but most areas of geotechnical. Calculation was compared with blast SPH and Eulerian model.