The underwater gliders are type of autonomous underwater vehicles, which are in their way to be used instead of traditional propellers or thrusters. They are used as submerged gliders or as a part connected to floating hull which is propelled by it. The underwater system depends on different number of hydrofoils (underwater wings) that allow it to glide forward while descending through the water. This paper concentrates on three critical design details: profile of the wings, multiple flapping wings and their angle of attack (AoA), and a method is focused on the mesh generation to predict calm water resistance for the submerged glider system while considering the profile and the maximum rotating angle of the wings and rudder. Flow around submerged wing system model has been calculated at different Froude numbers ranging from 0.1 to 0.6. The grid generator is established for meshing the computational domain with structured hexahedral and unstructured tetrahedral grid. Simulations are carried out using commercial CFD code ANSYS Fluent 19 to calculate calm water resistance of the submerged glider system with different number of hydrofoils. The results conclude that the cambered plate was chosen to design the rudder at 19 o AOA and the hydrofoil NACA0012 can be practically applied in the design of the wings at 15 o AOA from the resistance point of view. In addition, this investigation introduces a new application for CFD calculations in estimating the resistance of the submerged glider system.

In this paper, the influence of cylinder liner partial surface texturing in the top and bottom dead centers proximities was investigated. That influence was compared to full stroke surface texturing in order to evaluate the function of texturing on the surface of cylinder bore of low-speed marine diesel engine to improve the tribological performance of ring-liner pairs. Cylinder liner texturing has been designed in the form of macro-scale circumferential parabolic bottom shape oil grooves, with different depth-to-width ratios and area coverage density. Average Reynolds equation has been applied considering the oil flow factors through the micro asperities. Oil grooves has been numerically represented through the oil film configuration between piston ring and cylinder liner. The solution provides the cyclic average values of friction force of hydrodynamic lubrication, boundary lubrication, and total friction force. Results showed that the partial surface texturing has the superiority in improving tribological behavior of piston ring rather than that associated with full surface texturing.