Coaxial rotor systems are appealing for multirotor drones, as they increase thrust without increasing the vehicle’s footprint. However, of a coaxial system is reduced compared to having rotors in line. It interest efficiency systems, both extend mission time and enable new capabilities. While some parameters have been explored, such rotor-to-rotor distance, influence pitch less understood. This...

The polar coordinate transformation (PCT) method has been extensively used to treat various singular integrals in the boundary element method (BEM). However, the resultant integrands of the PCT tend to become nearly singular when (1) the aspect ratio of the element is large or (2) the field point is closed to the element boundary; thus a large number of quadrature points are needed to achieve a...

Dynamic analysis of a pile embedded in a half-space soil covered by a water layer is crucial for the designs of the pile foundations for bridges, docks and offshore platforms etc. In this paper, a coupled boundary element method (BEM) model is developed to evaluate the dynamic response of the pile. In the proposed model, the pile and half-space soil are treated as elastic media, while the water...

Only very recently, Sayas [The validity of Johnson-Nédélec's BEM-FEM coupling on polygonal interfaces. SIAM J Numer Anal 2009;47:3451-63] proved that the Johnson-Nédélec one-equation approach from [On the coupling of boundary integral and finite element methods. Math Comput 1980;35:1063-79] provides a stable coupling of finite element method (FEM) and boundary element method (BEM). In our work,...

The physically correct capture of propeller-rudder interaction is important if ship self-propulsion parameters are to be accurately predicted. Full resolution of a time accurate computational fluid dynamics calculation based on the Reynolds Averaged Navier Stokes equations requires a significant computational resource. The axial and tangential accelerations generated in the flow by the passage ...

ANALYSIS OF WIND TURBINE BLADE VIBRATION AND DRIVETRAIN LOADS By Venkatanarayanan Ramakrishnan The reliability of wind turbines is a major issue for the industry. Drivetrain and blade failures are common, costly and not fully understood. Designers must thus examine and understand the key parameters that influence reliability. As wind turbines increase in size, the blades are designed to be more...

A formulation and an implementation of two-dimensional Boundary Element Method (BEM) analysis for steady state, uncoupled thermoelastic problems is presented. This approach differs from other treatments of thermal loads in BEM analysis in which the domain integrals due to the thermal gradients are to be incorporated in the analysis via particular-integrals. Thus unlike Finite Elements or Field ...

Ship rudders are almost always placed downstream of the propeller so they can take advantage of the increased local velocity due to the presence of the propeller race. The methods discussed in this paper replicate the flow integrated effects of the propeller which generates an accelerated and swirled onset flow onto the rudder. As long as the radial variation in axial and tangential momentum (i...