Fish are particularly sensitive to connectivity loss as their ability to reach spawning grounds is seriously affected. The most common way to circumvent a barrier to longitudinal connectivity, and to mitigate its impacts, is to implement a fish passage device. However, these structures are often non-effective for species with different morphological and ecological characteristics so there is a ...

We discuss a new numerical scheme involving adaptive boundary conditions which allows to compute, at very low Reynolds numbers, drag and lift of airfoils with rough surfaces efficiently with great precision. As an example we present the numerical implementation for an airfoil consisting of a line segment. The solution of the NavierStokes equations is singular at the leading and the trailing edg...

The present paper contributes to the modeling of unsteady flow analysis of vertical axis wind turbine (VAWT). Double multiple stream tube (DSMT) model was applied for the performance prediction of straight bladed fixed pitch VAWT using NACA0018 airfoil at low wind speed. A moving mesh technique was used to investigate two-dimensional unsteady flow around the same VAWT model with NACA0018 airfoi...

Acoustic signature of a rigid wing, equipped with a movable downstream flap and interacting with a line vortex, is studied in a two-dimensional low-Mach number flow. The flap is attached to the airfoil via a torsion spring, and the coupled fluid-structure interaction problem is analyzed using thin-airfoil methodology and application of the emended Brown and Michael equation. It is found that in...

The considered multi-point (multi-objective) optimization problem is characterized by a multi-modal, nonlinear topology and a highly sophisticated evaluation of the objective function, thus requiring an efficient, direct global optimization algorithm. Evolution strategies have shown their capabilities for solving complex optimization problems with continuous variables in a variety of applicatio...

An episodic unsupervised learning simulation using the Q-Learning method is developed to learn the optimal shape and shape change policy for a problem with four state variables. Optimality is addressed by reward functions based on airfoil properties such as lift coefficient, drag coefficient, and moment coefficient about the leading edge representing optimal shapes for specified flight conditio...

This paper numerically investigates the effect of chordwise flexibility on the dynamic stability of compliant airfoils. A classical two-dimensional aeroelastic model is expanded with an additional degree of freedom to capture time-varying camber deformations, defined by a parabolic bending profile of the mean aerodynamic chord. Aerodynamic forces are obtained from unsteady thin airfoil theory a...

This paper presents an investigation on the effect of introducing large-scale roughness through static curvature modifications on the low speed flow over an airfoil. The surfaces of a standard Eppler 398 airfoil have been modified with regular perturbations or “bumps” of the order of 2%c for this purpose. While the actual E398 airfoil is not a suitable candidate for low Re cases due to extensiv...

The reported case describes a mismanaged extensive recurrent plunging ranula that occupied a large portion of the neck. The ranula is usually clinically diagnosed. However, absence of visible intra-oral signs may mislead the diagnosis and leads to improper surgical management. Presence of amylase in the aspirated fluids is an important aid in the differential diagnosis. Thereby confirming the s...

Ranulas are cystic lesions which results from rupture or damage of ducts of the sublingual glands leading to mucus extravasation or dilatation of the gland's duct. Extravasation cysts are more common as compared to retention cysts. Ranula mostly arises from sublingual glands and involvement of the submandibular gland is rare. Ranula often protrudes into the floor of the mouth, having only an or...