Experimental Validation of a Bio-Inspired Thruster

2021 ◽  
Vol 143 (8) ◽  
Author(s):  
Daniele Costa ◽  
Giacomo Palmieri ◽  
David Scaradozzi ◽  
Massimo Callegari
Keyword(s):  
Fluid Dynamics ◽  
Autonomous Underwater Vehicles ◽  
Measurement Techniques ◽  
Marine Animal ◽  
Marine Animals ◽  
Numerical Predictions ◽  
Invaluable Tool ◽  
Potential Benefits ◽  
Oscillating Foil ◽  
Future Work

Abstract Bio-inspired solutions have been deeply investigated in the last two decades as a source of propulsive improvement for autonomous underwater vehicles. Despite the efforts made to pursue the substantial potential payoffs of marine animals' locomotion, the performance of biological swimmers is still far to reach. The possibility to design a machine capable of propelling itself like a marine animal strongly depends on the understanding of the mechanics principles underlying biological swimming. Therefore, the adoption of advanced simulation and measurement techniques is fundamental to investigate the fluid–structure interaction phenomena of aquatic animals' locomotion. Among those, computational fluid dynamics represents an invaluable tool to assess the propulsive loads due to swimming. However, the numerical predictions must be validated before they can be applied to the design of a bio-inspired robot. To this end, this paper presents the experimental setup devised to validate the fluid dynamics analysis performed on an oscillating foil. The numerical predictions led to the design of a strain gages-based sensor, which exploits the deflection and twisting of the foil shaft to indirectly measure the propulsive loads and obtain a complete dynamic characterization of the oscillating foil. The results obtained from the experiments showed a good agreement between the numerical predictions and the measured loads; the test equipment also allowed to investigate the potential benefits of a slender fish-like body placed before the spinning fin. Therefore, in future work, the system will be employed to validate the analysis performed on more sophisticated modes of locomotion.

Biotic and Abiotic Controls on the Phanerozoic History of Marine Animal Biodiversity

2021 ◽  
Vol 52 (1) ◽  
Author(s):  
Andrew M. Bush ◽  
Jonathan L. Payne
Keyword(s):  
Biotic Interactions ◽  
Annual Review ◽  
Publication Date ◽  
Data Sets ◽  
Marine Animal ◽  
Marine Animals ◽  
Marine Habitat ◽  
Positive Feedbacks ◽  
Abiotic Controls ◽  
Time Changes

During the past 541 million years, marine animals underwent three intervals of diversification (early Cambrian, Ordovician, Cretaceous–Cenozoic) separated by nondirectional fluctuation, suggesting diversity-dependent dynamics with the equilibrium diversity shifting through time. Changes in factors such as shallow-marine habitat area and climate appear to have modulated the nondirectional fluctuations. Directional increases in diversity are best explained by evolutionary innovations in marine animals and primary producers coupled with stepwise increases in the availability of food and oxygen. Increasing intensity of biotic interactions such as predation and disturbance may have led to positive feedbacks on diversification as ecosystems became more complex. Important areas for further research include improving the geographic coverage and temporal resolution of paleontological data sets, as well as deepening our understanding of Earth system evolution and the physiological and ecological traits that modulated organismal responses to environmental change. Expected final online publication date for the Annual Review of Ecology, Evolution, and Systematics, Volume 52 is November 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Metal Temperature Prediction of a Dry Low NOx Class Flame Tube by Computational Fluid Dynamics Conjugate Heat Transfer Approach

2015 ◽  
Vol 138 (3) ◽  
Author(s):  
Riccardo Da Soghe ◽  
Cosimo Bianchini ◽  
Antonio Andreini ◽  
Lorenzo Mazzei ◽  
Giovanni Riccio ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Operating Conditions ◽  
Metal Temperature ◽  
Thermal Loads ◽  
Flame Tube ◽  
Numerical Predictions ◽  
Partial Load ◽  
Critical Components

Combustor liner of present gas turbine engines is subjected to high thermal loads as it surrounds high temperature combustion reactants and is hence facing the related radiative load. This generally produces high thermal stress levels on the liner, strongly limiting its life expectations and making it one of the most critical components of the entire engine. The reliable prediction of such thermal loads is hence a crucial aspect to increase the flame tube life span and to ensure safe operations. The present study aims at investigating the aerothermal behavior of a GE Dry Low NOx (DLN1) class flame tube and in particular at evaluating working metal temperatures of the liner in relation to the flow and heat transfer state inside and outside the combustion chamber. Three different operating conditions have been accounted for (i.e., lean–lean partial load, premixed full load, and primary load) to determine the amount of heat transfer from the gas to the liner by means of computational fluid dynamics (CFD). The numerical predictions have been compared to experimental measurements of metal temperature showing a good agreement between CFD and experiments.

scholarly journals Autonomous Underwater Vehicle in Internet of Underwater Things: A Survey

2021 ◽  
Vol 2129 (1) ◽  
pp. 012080
Author(s):  
Chinonso Okereke ◽  
Nur Haliza Abdul Wahab ◽  
Mohd Murtadha Mohamad ◽  
S H Zaleha
Keyword(s):  
Energy Storage ◽  
Crucial Role ◽  
Autonomous Underwater Vehicle ◽  
Autonomous Underwater Vehicles ◽  
Underwater Vehicle ◽  
Underwater Vehicles ◽  
The Internet ◽  
The Earth ◽  
Future Work

Abstract Water, mostly oceans, covers over two-third of the earth. About 95% of these oceans are yet to be explored which includes 99% of the sea-beds. The introduction of the Internet of Underwater Things (IoUT) underwater has become a powerful technology necessary to the quest to develop a SMART Ocean. Autonomous Underwater Vehicles (AUVs) play a crucial role in this technology because of their mobility and longer energy storage. In order for AUV technologies to be effective, the challenges of AUVs must be adequately solved. This paper provides an overview of the challenges of IoUT, the contributions of AUVs in IoUT as well as the current challenges and opening in AUV. A summary and suggestion for future work was discussed.

Computational Fluid Dynamics Modeling of Gaseous Cavitation in Lubricating Vane Pumps: An Approach Based on Dimensional Analysis

2020 ◽  
Vol 142 (7) ◽  
Author(s):  
Umberto Stuppioni ◽  
Alessio Suman ◽  
Michele Pinelli ◽  
Alessandro Blum
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Dimensional Analysis ◽  
Operating Conditions ◽  
Cfd Modeling ◽  
Dynamic Features ◽  
Dynamics Modeling ◽  
Vane Pump ◽  
Numerical Predictions ◽  
Pressure Ripple

Abstract This paper addresses the problem of computational fluid dynamics (CFD) modeling of gaseous cavitation (GC) in lubricating positive-displacement pumps (PDPs). It is important for designers and analysts to predict the dynamic features of air release/dissolution processes which characterize this phenomenon, along with their effects on filling capability and noise-vibration-harshness behavior of the machine. The focus is on the empirical tuning of the commercial homogeneous-flow cavitation model known as dissolved gas model (DGM). Considering an automotive case study of a balanced vane pump (BVP), the effects of air modeling on numerical predictions of discharge flow/pressure ripple and volumetric efficiency have been studied. The tuning time parameters of the model have been correlated to the machine Reynolds number as part of a simplified theoretical background based on dimensional analysis. Considering experimental data at different operating conditions, the tuned model has shown a good capacity in predicting the pressure ripple and the flowrate at the discharge of the pump.

Interfacing Virtual Reality, CFD and the Internet

1997 ◽  
Author(s):  
David J. Freeman
Keyword(s):  
Fluid Dynamics ◽  
Virtual Reality ◽  
The Internet ◽  
Parallel Processor ◽  
Computing Power ◽  
Numerical Predictions ◽  
Computational Fluid Dynamics Cfd ◽  
Software And Hardware ◽  
Time Required ◽  
The Cost

Computational Fluid Dynamics (CFD) is a valuable tool for the process and petroleum industries. CFD reduces development timescales and costs by replacing expensive and lengthy laboratory investigation with numerical predictions of processes. However, there are several reasons why some companies are unwilling to use CFD. These include the cost of the software and hardware, the need for in-house CFD expertise and the time required to solve complex simulations. CHAM has developed a solution to these problems, in the form of a Virtual Reality Interface linked via the Internet to powerful parallel-processor computers. Virtual reality makes CFD accessible to non-CFD experts and allows the engineer to concentrate on the solution of his problem. Remote computing makes it possible to access from a PC the necessary computing power to solve the problem. Several examples will be shown, demonstrating the application and benefits of the PHOENICS-VR interface and the advantages of remote computing to the process and petroleum industries.

scholarly journals Linking dimensions of data on global marine animal diversity

2020 ◽  
Vol 375 (1814) ◽  
pp. 20190445 ◽  
Author(s):  
Thomas J. Webb ◽  
Bart Vanhoorne
Keyword(s):  
Functional Groups ◽  
Current Knowledge ◽  
Conservation Status ◽  
Marine Conservation ◽  
Marine Animal ◽  
Multiple Sources ◽  
Marine Animals ◽  
Research Perspectives ◽  
Animal Diversity ◽  
Marine Diversity

Recent decades have seen an explosion in the amount of data available on all aspects of biodiversity, which has led to data-driven approaches to understand how and why diversity varies in time and space. Global repositories facilitate access to various classes of species-level data including biogeography, genetics and conservation status, which are in turn required to study different dimensions of diversity. Ensuring that these different data sources are interoperable is a challenge as we aim to create synthetic data products to monitor the state of the world's biodiversity. One way to approach this is to link data of different classes, and to inventory the availability of data across multiple sources. Here, we use a comprehensive list of more than 200 000 marine animal species, and quantify the availability of data on geographical occurrences, genetic sequences, conservation assessments and DNA barcodes across all phyla and broad functional groups. This reveals a very uneven picture: 44% of species are represented by no record other than their taxonomy, but some species are rich in data. Although these data-rich species are concentrated into a few taxonomic and functional groups, especially vertebrates, data are spread widely across marine animals, with members of all 32 phyla represented in at least one database. By highlighting gaps in current knowledge, our census of marine diversity data helps to prioritize future data collection activities, as well as emphasizing the importance of ongoing sustained observations and archiving of existing data into global repositories. This article is part of the theme issue ‘Integrative research perspectives on marine conservation’.

Experimental and Numerical Investigation of Rotating Bladed Disk Forced Response Using Underplatform Friction Dampers

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Ibrahim A. Sever ◽  
Evgeny P. Petrov ◽  
David J. Ewins
Keyword(s):  
Measurement Techniques ◽  
Measured Data ◽  
Forced Response ◽  
Imperial College ◽  
Test Rig ◽  
Response Curves ◽  
Friction Dampers ◽  
Bladed Disk ◽  
Prediction Tools ◽  
Numerical Predictions

In this paper, we present a methodology and results from an experimental investigation of forced vibration response for a bladed disk with fitted underplatform “cottage-roof” friction dampers, together with the corresponding numerical predictions. A carefully designed and constructed rotating test rig is used to make precise measurements, which involve only the phenomena of interest. For this purpose, the measurement rig is operated under vacuum to eliminate aerodynamic effects on the rotating blisk and noncontact excitation and measurement techniques are employed so as not to modify the bladed disk dynamics. The experimental data measured are used for validation of multiharmonic balance-based prediction tools developed at the Imperial College. Predictions are carried out both with and without taking inherent mechanical mistuning into account, which is identified from measured data. Measured and predicted response curves are compared with each other and the degree of correlation is discussed.

The fate of fossil fuel hydrocarbons in marine animals

1975 ◽  
Vol 189 (1096) ◽  
pp. 391-413 ◽  
Keyword(s):  
Aromatic Hydrocarbons ◽  
Animal Species ◽  
Fossil Fuel ◽  
Marine Animal ◽  
Marine Animals ◽  
Marine Food Web ◽  
Polycyclic Aromatic ◽  
Marine Food ◽  
The Many ◽  
Uptake And Release

Certain hydrocarbons present in crude oil have been detected in several marine animal species as well as algae and sediments. The importance of pollution as a source of these hydrocarbons is briefly considered, as is evidence for their biosynthesis in marine organisms. The problem of whether these compounds, particularly the polycyclic aromatic hydrocarbons, are transferred through the marine food web is considered in the light of recent evidence for their uptake and release by various marine animals; and the question of whether they are excreted unchanged or as metabolites is discussed in the context of the many studies that have been made of their fate in mammals.

scholarly journals Layout Effect of Two Autonomous Underwater Vehicles on the Hydrodynamics Performances

2020 ◽  
Vol 19 ◽  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Autonomous Underwater Vehicles ◽  
Three Dimensional ◽  
Pressure Change ◽  
Underwater Vehicles ◽  
Optimal Layout ◽  
Minimum Drag ◽  
Computational Fluid Dynamics Cfd ◽  
Two Parameters

Three-dimensional computational fluid dynamics (CFD) is used for the design optimization of the layout of an autonomous underwater vehicles (AUV) containing three torpedo-shaped hulls. The AUV layout is defined by two parameters a and b present the stance following YY and XX respectively. several simulations are carried on the AUV with different positions of the torpedo in order to define the optimal layout which designates the minimum drag. the numerical results approve that the variation in the drag coefficient of the AUV is the to the interaction of the flow rate and the pressure change between the both hulls. in addition, an optimal layout for the minimum AUV drag with two torpedoes is found which provides a drag reduce of about 11.4% lower than a single UV with a single torpedo.

Microfabricated Cavities for Adhesive Capture of Stem Cells Under Flow

2007 ◽  
Author(s):  
Dooyoung Lee ◽  
Kuldeepsinh Rana ◽  
Karin Lee ◽  
Lisa A. DeLouise ◽  
Michael R. King
Keyword(s):  
Fluid Dynamics ◽  
Stem Cells ◽  
Computational Fluid Dynamics ◽  
Blood Flow ◽  
Shear Stresses ◽  
Computational Fluid Dynamics Cfd ◽  
Future Work ◽  
Flow Experiments

In previous work, we have described the adhesive capture of circulating stem cells to surfaces coated with adhesive selectin protein, both in vitro and in vivo. Here we describe PDMS surfaces microfabricated to contain an array of square 80 × 80 × 80 micron cavities. These cavities are intended to provide a local bioreactor environment to culture stem cells over extended periods of time, while sheltered from the higher shear stresses of the surrounding blood flow external of the cavities. In this paper we present in vitro flow experiments with polymeric, blood cell-sized microspheres, showing the creation of stable vortices within the microscale cavities. Computational fluid dynamics (CFD) was performed to predict the velocity field within the cavity, and for comparison with experimentally determined microsphere velocities. Future work will establish the ability to place local chemoattract molecules within the cavity interior, and the ability to accumulate viable stem cells within these cavities.

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