A multi-objective optimization design framework integrated with CFD for the design of AUVs

Recently, the importance of design process with unknown parameter increased. On the other hand, the design of Autonomous Underwater Vehicles (AUVs) is a difficult challenge since it requires the consideration of various aspects such as mission range, controllability, energy source, and carrying capacity. A design process for novel type of AUV constructed using an origami-based structure that includes active material actuators and solar panels is proposed in this paper. To increase the efficiency in the three-dimensional shape modeling of the AUV, the shape of the outer surface is parameterized by a finite set of variables using shape functions. Here, the AUV should operate underwater via electrical power with the batteries being charged periodically using solar panels. The ability of the AUV to transport cargo such as instrumentation is also addressed. The design parameters include the total height and width of the AUV. As these dimensions of the AUV might vary in a non-preferential manner based on particular mission goals, these dimensions are considered as design parameters in a multi-objective optimization setting. The Predictive Parameterized Pareto Genetic Algorithm (P3GA) is selected as the optimization method to determine a Pareto frontier of design options with desired characteristics for a variety of missions for the AUV. The evaluation of each AUV design entails quantitative assessment of the origami fold pattern determined using a method developed by the authors and Computational Fluid Dynamics (CFD) analysis. The development of a design process that addresses the design optimization of the AUV considering its hydrodynamic performance and origami aspects is the main topic of this paper.

This study focuses on conceptualizing and optimizing an advanced bionic robotic solution to surmount the limitations of current observational vehicles in coral reef conservation. Human divers are traditionally subjected to physiological challenges, while current robotic alternatives grapple with operational impediments, including anthropogenic marine disturbances. Utilizing advanced robotics tailored for marine ecosystems with intricate topologies and fragile corals, this study aims to enhance conservation precision in the face of climatic shifts and marine pollution from anthropogenic activities.This paper develops a squid-inspired Autonomous Underwater Vehicle (AUV), whose behavior is then examined and improved utilizing both experiments and Computational Fluid Dynamics.(CFD). The governing equations considered here are the incompressible Reynolds-Averaged Navier-Stokes (RANS) with an iterative solver for both the pressure-Poisson and momentum equations. Apart from CFD analysis, a prototype was assembled and experimentally tested to validate the CFD outcomes and assess the lift from its bionic rudders. The maneuverability is optimized through careful designs and parameter studies of several features.A head length is determined to balance viscous and pressure drag while achieving the least total drag in the AUV design. Additionally, a disk is introduced at the AUV’s front, which reduces fluid contact, thereby decreasing the viscous drag. While this modification slightly increased pressure drag, it yielded an overall reduction in total drag. Experimental observations confirmed a propulsion speed and underscored the necessity for maximizing rudder extension.The developed AUV’s squid-like design, optimized via CFD, ensures drag reduction by 5.34% and energy efficiency. By mimicking squid dynamics, disturbances to marine biota are minimized. The incorporation of bionic fins, empirically fine-tuned, enhances the AUV’s agility. These attributes establish it as an exceptional prototype, setting a precedent for future coral reef monitoring systems and augmenting conservation strategies.

A general method is proposed for design and development of a low-speed AUV (Autonomous Underwater Vehicle) ANAHITA. Due to the complex geometry of this AUV, it is very difficult to identify its dynamic and hydrodynamic parameters theoretically. Therefore, the objective of this paper is to first discuss the design of AUV and then to find an efficient modeling approach, whose results can be used for accurate control model design. The presented approach uses cost efficient CFD (Computational Fluid Dynamics) softwares, predicting the two hydrodynamic key parameters: the Added Mass Matrix and the Damping Matrix. A complete model is built for ANAHITA for CFD analysis.

A software system's architecture provides a model of the system that suppresses implementation detail, allowing the architect to concentrate on the analysis and decisions that are most crucial to structuring the system to satisfy its requirements, specially including time constraints. In his paper, we propose a timed model for an architecture for software systems with time constraints and investigate structural and behavioral relations among timed components and the composite of them in this model. These work will be likely used for consistency testing and verification of component-based analysis and development for real-time systems.

Floodways, where a road embankment is permitted to be overtopped by flood water, are usually designed as broad-crested weirs. Determination of the water level above the floodway is crucial and related to road safety. Hydraulic performance of floodways can be assessed numerically using 1-D modelling or 3-D simulation using computational fluid dynamics (CFD) packages. Turbulence modelling is one of the key elements in CFD simulations. A wide variety of turbulence models are utilized in CFD packages; in order to identify the most relevant turbulence model for the case in question, 96 3-D CFD simulations were conducted using Flow-3D package, for 24 broad-crested weir configurations selected based on experimental data from a previous study. Four turbulence models (one-equation, k-ε, RNG k-ε, and k-ω) ere examined for each configuration. The volume of fluid (VOF) algorithm was adopted for free water surface determination. In addition, 24 1-D simulations using HEC-RAS-1-D were conducted for comparison with CFD results and experimental data. Validation of the simulated water free surface profiles versus the experimental measurements was carried out by the evaluation of the mean absolute error, the mean relative error percentage, and the root mean square error. It was concluded that the minimum error in simulating the full upstream to downstream free surface profile is achieved by using one-equation turbulence model with mixing length equal to 7% of the smallest domain dimension. Nevertheless, for the broad-crested weir upstream section, no significant difference in accuracy was found between all turbulence models and the one-dimensional analysis results, due to the low turbulence intensity at this part. For engineering design purposes, in which the water level is the main concern at the location of the flood way, the one-dimensional analysis has sufficient accuracy to determine the water level.

There is a diversity of shapes and sensor configurations used in the design of autonomous underwater vehicles (AUVs). Cameras and lighting (for both still and video imaging) are common sensor systems and have traditionally been configured to produce orthogonal images of the seafloor. Such imagery provides invaluable small-scale, high-resolution data for studies of seafloor geology and sessile invertebrate communities. However, using orthogonal imagery to census the diversity of mobile fauna has limitations caused by avoidance. A simple analysis using species-individual curves demonstrated that species richness was generally lower in surveys using orthogonal images when compared to forward-looking oblique images despite encountering the same number of individual fishes. This pattern was consistent when contrasting data from separate AUV and ROV surveys at boulder reefs in the Gulf of Maine as well as from down-looking and forward-looking cameras simultaneously collecting video imagery from a camera sled in a variety of habitats. These results indicate a need to evaluate the effects of camera configuration on the performance of abundance and diversity indicators developed from image data acquired using AUVs and other vehicles. Further, we recommend that AUV designers endeavor to accommodate oblique angles for cameras and associated lighting within vehicle design parameters in order to support missions that improve detection of mobile fauna.

The flexible transmission shaft and wheel propeller are combined as the kinetic source equipment, which realizes the multi-motion modes of the autonomous underwater vehicle (AUV) such as vectored thruster and wheeled movement. In order to study the interactional principle between the hull and the wheel propellers while the AUV navigating in water, the computational fluid dynamics (CFD) method is used to simulate numerically the unsteady viscous flow around AUV with propellers by using the Reynolds-averaged Navier-Stokes (RANS) equations, shear-stress transport (SST) k-w model and pressure with splitting of operators (PISO) algorithm based on sliding mesh. The hydrodynamic parameters of AUV with propellers such as resistance, pressure and velocity are got, which reflect well the real ambient flow field of AUV with propellers. Then, the semi-implicit method for pressure-linked equations (SIMPLE) algorithm is used to compute the steady viscous flow field of AUV hull and propellers, respectively. The computational results agree well with the experimental data, which shows that the numerical method has good accuracy in the prediction of hydrodynamic performance. The interaction between AUV hull and wheel propellers is predicted qualitatively and quantitatively by comparing the hydrodynamic parameters such as resistance, pressure and velocity with those from integral computation and partial computation of the viscous flow around AUV with propellers, which provides an effective reference to the study on noise and vibration of AUV hull and propellers in real environment. It also provides technical support for the design of new AUVs.

Results are presented from a numerical simulation of three-dimensional flow hydraulics around a mid-channel bar carried out using the FLUENT/UNS computational fluid dynamics (CFD) software package. FLUENT/UNS solves the three-dimensional Reynolds-averaged form of the Navier–Stokes equations. Turbulence closure is achieved using a RNG k–ϵ model. Simulated flow velocities are compared with measured two-dimensional velocities (downstream and cross-stream) obtained using an electromagnetic current meter (ECM). The results of the simulation are qualitatively consistent with the flow structures observed in the field. Quantitative comparison of the simulated and measured velocity magnitudes indicates a strong positive correlation between the two (r=0·88) and a mean difference of 0·09 m s−1. Deviations between simulated and measured velocities may be identified that are both random and systematic. The former may reflect a number of factors including subgrid-scale natural spatial variability in flow velocities associated with local bed structures and measurement uncertainty resulting from problems of ECM orientation. Model mesh configuration, roughness parameterization and inlet boundary condition uncertainty may each contribute to systematic differences between simulated and measured flow velocities. These results illustrate the potential for using CFD software to simulate flow hydraulics in natural channels with complex configurations. They also highlight the need for detailed spatially distributed datasets of three-dimensional flow variables to establish the accuracy and applicability of CFD software. Copyright © 1999 John Wiley & Sons, Ltd.

Modeling of energy production and heat transfer by carbon combustion and electrical arc is performed using Fluent computational fluid dynamic (CFD) software in this manuscript. The heat energy generated by carbon burning and electric arc radiation during combustion of the scrap in the EAO has been examined in detail. For this reason, modeling studies have utilized the combustion reactions of carbon particles and electromagnetically emitted radiation. Firstly, particle surface and gas reactions are investigated in terms of injected carbon burning. The result of the chemical reaction at the burner outlet is about 3000 K of the core temperature during combustion. It has been determined that the temperature which acts on the slag is 2200 K. The radiation temperature was found to be highest in the area under the electrodes and fell to 1850 K in the area where the melt was poured. Under steady operating conditions, it was seen that electric energy was absorbed by about 5.5% of the electrodes. As a result of this study, CFD software can be used to model combustion and radiation and energy generation and heat transfer for an electric arc furnace at the design study.

Industrial development and surveying projects related to oil and natural gas resources and undersea pipelines require comprehensive geological, geophysical, and oceanographic research to be conducted in offshore and coastal areas. These research activities are typically conducted by research vessels or smaller craft that are specially equipped for specific tasks, which often require considerable labour. However, this research method incurs high operating costs and poses risks to occupational safety and property, particularly due to the harsh weather conditions at sea. In addition, high-precision measurements cannot always be effectively taken using these vessels at the sea surface during such projects. Consequently, research institutions and organisations have made significant advancements in developing autonomous underwater vehicles (AUVs) over the past two decades. The aim of this study was to identify an optimal design form for AUVs to enable them to examine the geomorphological, geological, and geophysical structures of the seafloor while also supporting oceanographic research. To achieve this, computational fluid dynamics analyses were conducted on the DARPA (Defense Advanced Research Projects Agency) Suboff submarine model, and the results were validated using experimental data obtained from the literature [1]. After successfully confirming the accuracy of the simulations, which were executed using the commercial software STAR CCM+ (Simulation of Turbulent Flow in Arbitrary Regions - Computational Continuum Mechanics, C++ based), various AUV designs were created based on commonly used geometric shapes for torpedoes. In addition, biomimicry principles were employed to develop AUV models with minimal viscous resistance and energy consumption during underwater operations. The following models, all with the same displacement, were systematically analysed: a mature goose-beaked whale (Ziphius cavirostris), a mature sperm whale (Physeter macrocephalus), an adapted form of the submarine shark (Carcharodon carcharias, also known as the great white shark), four biomimicry-inspired hybrid models and four torpedo-shaped AUVs. The findings from these analyses are discussed in detail.

This study focused on the development of an autonomous Underwater Vehicle (AUV) across four key domains: Mechanical Design, Software, Electronics, and Security. The Mechanical Design phase involved utilizing computer-aided drawing programs to create the AUV model. Important design considerations encompassed manufacturability, cost, power, weight, and durability. Comparisons with nominal values of existing market products validated the precision of the produced designs. Particular emphasis was placed on optimizing the weight of the models, ensuring the AUV's efficiency, lightness, and exceptional maneuverability in underwater environments. The Software stage entailed the development of AUV software to enable sensitive and effective vehicle operations. Seamless functioning, devoid of errors or complications, was imperative to ensure optimal autonomous driving, running, and operational capabilities. Image processing algorithms were incorporated into the software to maintain high accuracy and provide dimensional and geometric information of targeted areas. Furthermore, the software phase involved the development of an image processing algorithm based on color analysis, further augmenting accuracy. The selection of electronic components for the AUV was also a vital consideration, alongside ensuring safety measures at every stage of the UAV's development.

Shape optimization of an autonomous underwater vehicle with a ducted propeller using computational fluid dynamics analysis

In this study, a computational fluid dynamics (CFD) model is applied to study the airflow patterns inside the commingling jets, for different configurations. The CFD package, FLUENT 6.1, is used to predict the two-dimensional flow field inside a yarn channel. The parameters viz. velocity profile, pressure gradient, and air particle trajectory, obtained from this CFD analysis give important information for further analysis. The design parameters of commingling jets are related to the flow characteristics and their effect on the structure and properties of Glass/Nylon commingled yarns. The results show that the number of air orifice and the angle of orifice have significant effect on the airflow profile inside the jet and consequently on the structure of the commingled yarns. The jet orifice angle affects the axial velocity. The effect of air pressure is also important, since the nip frequency of commingled yarns is a function of the speed of rotation of the vortex and it is observed that with increase in air pressure, axial and tangential velocities in the nozzle increase. This work shows that, the CFD modeling can be used to optimize nozzle design parameters to develop commingled yarns with better properties.

A synergetic approach to the conceptual design of Autonomous Underwater Vehicle

Biological inspiration from fish has played a key role in the design of Autonomous Underwater Vehicles (AUVs). For example, the manta ray’s use of medial paired fins (MPF) as its primary means of thrust production serves as a model due to its exceptional maneuverability, inherent stability, and efficient locomotion. However, researchers have yet to achieve the high locomotor efficiency observed in MPF-swimming animals. This work proposes a bio-inspired pectoral fin design coupled with compliant tensegrity joint design to achieve locomotive efficiency as the primary design target. The actuated fin offers compliance in both the fin’s spanwise and chordwise directions by utilizing a flexible 3D printed skeleton cast within a silicone rubber matrix to assist with load transmission from the actuator. The fin is actuated through a novel dual tensegrity revolute joint actuator driven by DC motors. The use of the proposed tensegrity joints for load transmission provides high torque output to the fin and mimics the natural stability of manta rays by offering built in compliance. The actuated chord of the fin is extended from the body so that inputs are applied in the net thrust producing region. The paper also details the fabrication methodology that incorporates a flexible skeleton inside silicone rubber fin and subsequent waterproofing.