scholarly journals A Computational Study of Hydrodynamic Interactions Between Pairs of Sperm With Planar and Quasi-Planar Beat Forms

2021 ◽  
Vol 9 ◽  
Author(s):  
Lucia Carichino ◽  
Derek Drumm ◽  
Sarah D. Olson
Keyword(s):  
Minimum Distance ◽  
Computational Study ◽  
Hydrodynamic Interactions ◽  
Key Factors ◽  
Confined Geometries ◽  
Image System ◽  
3 Dimensional ◽  
Structure Interaction ◽  
Mammalian Sperm ◽  
Constant Distance

Although hydrodynamic interactions and cooperative swimming of mammalian sperm are observed, the key factors that lead to attraction or repulsion in different confined geometries are not well understood. In this study, we simulate the 3-dimensional fluid-structure interaction of pairs of swimmers utilizing the Method of Regularized Stokeslets, accounting for a nearby wall via a regularized image system. To investigate emergent trajectories of swimmers, we look at different preferred beat forms, planar or quasi-planar (helical with unequal radii). We also explored different initializations of swimmers in either the same plane (co-planar) or with centerlines in parallel planes. In free space, swimmers with quasi-planar beat forms and those with planar beat forms that are co-planar exhibit stable attraction. The swimmers reach a maintained minimum distance apart that is smaller than their initial distance apart. In contrast, for swimmers initialized in parallel beat planes with a planar beat form, we observe alternating periods of attraction and repulsion. When the pairs of swimmers are perpendicular to a nearby wall, for all cases considered, they approach the wall and reach a constant distance between swimmers. Interestingly, we observe sperm rolling in the case of swimmers with preferred planar beat forms that are initialized in parallel beat planes and near a wall.

Computational Study of a Subsonic Aircraft Design: Basic CFD Methods and CAD Designs

2008 ◽  
Author(s):  
Scott Winkelmann ◽  
Ryoichi S. Amano
Keyword(s):  
Computational Study ◽  
Aircraft Design ◽  
Tetrahedral Mesh ◽  
Hexahedral Mesh ◽  
3 Dimensional ◽  
Dimensional Modeling ◽  
Basic Understanding ◽  
Modeling Software ◽  
Simple Features ◽  
Meshing Process

This investigation explores the methodology, using various computational tools and processes, involved in designing the fuselage of an aircraft. The design begins using 3-Dimensional modeling software and a basic understanding of aerodynamics. The form of the aircraft is built using only a few simple features and is then ready for the meshing process. Picking a simple tetrahedral mesh, rather than a more complicated hexahedral mesh, will allow this process to proceed even faster and also requires only a basic understanding of meshing. Once the geometry is completed the mesh may be moved into Computational Fluid Dynamics software and a wind tunnel simulation can be preformed. Developing a connection between each of these steps will allow the design to be manipulated in many different ways.

Computational Study of Pressure Pulsation in a Medium Specific Speed Pump

2005 ◽  
Author(s):  
Serguei Timouchev
Keyword(s):  
Complex Geometry ◽  
Computational Study ◽  
Spectral Component ◽  
Axial Component ◽  
Centrifugal Pumps ◽  
Pressure Pulsations ◽  
3 Dimensional ◽  
Order Of Magnitude ◽  
Specific Speed ◽  
In The Beginning

The centrifugal pump of high specific speed with a diagonal type of impeller flow is studied experimentally and numerically. Both 2D and 3D numerical methods are used by applying acoustics–vortex equations. Increasing energetic parameters of centrifugal pumps requires a more complex geometry of the impeller and volute as one needs to raise the specific speed of the pump to provide a higher efficiency value. The pump of higher specific speed has an impeller with curved blades and diagonal meridional section. The flow outgoing the impeller has an essential axial component of velocity. Thus the two dimensional approach will not give the accurate prediction of pressure pulsations in the volute casing. This is why the new 3-dimensional method has been elaborated for this task. The 3D computational results of pressure pulsations are compared with those obtained by 2D-computation Measurements show that in the beginning of volute, in the pseudo-sound zone, amplitude of Blade Passing Frequency (BPF) spectral component is higher than that at the pump outlet by an order of magnitude. The 3-Dimensional analysis gives a good agreement with experimental data while the 2D prediction underestimates the BPF amplitude in the beginning of volute.

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