Computational Fluid Dynamics Study of Water Entry Impact Forces of an Airborne-Launched, Axisymmetric, Disk-Type Autonomous Underwater Hovering Vehicle

Chen, Chen-Wei; Lu, Yifan

doi:10.3390/sym11091100

Cited by 11 publications

(6 citation statements)

References 20 publications

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“…Both air and water are assumed to be incompressible in the numerical simulation, where temperature alterations are disregarded. Subsequently, the following continuity equation along with a Reynolds-averaged Navier-Stokes (RANS) system is formulated [25]:…”

Section: Governing Equationsmentioning

confidence: 99%

Investigation of the Impact Load Characteristics during Water Entry of Airdropped Underwater Gliders

Wu,

et al. 2024

JMSE

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Underwater gliders have emerged as effective tools for long-term ocean exploration. Employing aircraft for launching underwater gliders could significantly expand their application. Compared to slender underwater vehicles, the distinctive wing structure of underwater gliders may endure huge impact forces when entering water, leading to more intricate impact load characteristics and potential wing damage. This paper employs a computational fluid dynamics approach to analyze the water entry event of an airdropped underwater glider and its impact load behavior. The results indicate that the glider impact load is enhanced prominently by the wing, and that the extent of enhancement is influenced by the entry attitude. At an entry angle of 80°, the glider exhibits the maximum impact load during different water entry angles. In addition, a larger attack angle indicates a higher glider impact load. Our present study holds significant importance for both the hydrodynamic shape design and water entry strategy control of airdropped underwater gliders.

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Section: Governing Equationsmentioning

confidence: 99%

Investigation of the Impact Load Characteristics during Water Entry of Airdropped Underwater Gliders

Wu,

et al. 2024

JMSE

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“… represents the nominal part that can be determined by the computational fluid dynamics (CFD) [36]. ( ) i Δ  denotes the difference between the actual and nominal parts, i.e., model uncertainties.…”

Section: Auv Modelingmentioning

confidence: 99%

Distributed Lyapunov-Based Model Predictive Control for AUV Formation Systems with Multiple Constraints

Yan,

Zhang,

Zhou

et al. 2024

JMSE

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This paper focuses on the formation tracking issue of autonomous underwater vehicles (AUVs) subject to multiple constraints in three-dimensional space. We developed a novel distributed Lyapunov-based model predictive controller (DLMPC) with a fast finite-time extended state observer (FFTESO). Initially, the external disturbances and internal uncertainties of each AUV were precisely compensated using the designed FFTESO. Subsequently, we proposed DLMPC-based position tracking and velocity tracking controllers, which solved an online optimization problem to determine optimal velocities and control forces. This hierarchical framework effectively managed system constraints, such as state constraints and actuator saturation. Additionally, the Lyapunov-based backstepping control law was applied to construct stability constraints in the distributed optimization problem, ensuring the recursive feasibility and closed-loop system stability of the proposed scheme. Sufficient conditions and attraction regions to ensure stability were explicitly provided. Finally, the simulation results demonstrated that the proposed method improved both the convergence speed and tracking accuracy by at least 30% compared to other methods.

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“…Numerical models are applicable for modeling the flow of fluid and heat transfer of complex geometries and operating conditions [48][49][50][51]. In the first step of the present modeling procedure, it is required to define the geometry of the microchannel.…”

Section: Numerical Modelmentioning

confidence: 99%

Numerical Investigation of Forced Convective Heat Transfer and Performance Evaluation Criterion of Al2O3/Water Nanofluid Flow inside an Axisymmetric Microchannel

et al. 2020

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Al2O3/water nanofluid conjugate heat transfer inside a microchannel is studied numerically. The fluid flow is laminar and a constant heat flux is applied to the axisymmetric microchannel’s outer wall, and the two ends of the microchannel’s wall are considered adiabatic. The problem is inherently three-dimensional, however, in order to reduce the computational cost of the solution, it is rational to consider only a half portion of the axisymmetric microchannel and the domain is revolved through its axis. Hence. the problem is reduced to a two-dimensional domain, leading to less computational grid. At the centerline (r = 0), as the flow is axisymmetric, there is no radial gradient (∂u/∂r = 0, v = 0, ∂T/∂r = 0). The effects of four Reynolds numbers of 500, 1000, 1500, and 2000; particle volume fractions of 0% (pure water), 2%, 4%, and 6%; and nanoparticles diameters in the range of 10 nm, 30 nm, 50 nm, and 70 nm on forced convective heat transfer as well as performance evaluation criterion are studied. The parameter of performance evaluation criterion provides valuable information related to heat transfer augmentation together with pressure losses and pumping power needed in a system. One goal of the study is to address the expense of increased pressure loss for the increment of the heat transfer coefficient. Furthermore, it is shown that, despite the macro-scale problem, in microchannels, the viscous dissipation effect cannot be ignored and is like an energy source in the fluid, affecting temperature distribution as well as the heat transfer coefficient. In fact, it is explained that, in the micro-scale, an increase in inlet velocity leads to more viscous dissipation rates and, as the friction between the wall and fluid is considerable, the temperature of the wall grows more intensely compared with the bulk temperature of the fluid. Consequently, in microchannels, the thermal behavior of the fluid would be totally different from that of the macro-scale.

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Computational Fluid Dynamics Study of Water Entry Impact Forces of an Airborne-Launched, Axisymmetric, Disk-Type Autonomous Underwater Hovering Vehicle

Cited by 11 publications

References 20 publications

Investigation of the Impact Load Characteristics during Water Entry of Airdropped Underwater Gliders

Investigation of the Impact Load Characteristics during Water Entry of Airdropped Underwater Gliders

Distributed Lyapunov-Based Model Predictive Control for AUV Formation Systems with Multiple Constraints

Numerical Investigation of Forced Convective Heat Transfer and Performance Evaluation Criterion of Al2O3/Water Nanofluid Flow inside an Axisymmetric Microchannel

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