Numerical simulation of cavitating flows under uncertainty

Abgrall, Rémi; Congedo, Pietro Marco

doi:10.1088/1742-6596/821/1/012009

Cited by 3 publications

(2 citation statements)

References 21 publications

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“…More specifically, the system response is expanded using an orthogonal polynomial form of uncertain stochastic variables, thus these stochastic characteristics are converted into the deterministic coefficients of PCE. Rodio, Abgrall, and Congedo (2017), Rodio and Congedo (2014) and Congedo, Goncalves, and Rodio (2015) adopted a non-intrusive PCE to quantify the uncertainty and its propagation for cavitation occurring in a venturi tube with a physical inlet, and modeled the parameters' uncertainties. After comparing the numerical solutions with error bars and experimental curves, flow field parameters presented a large sensitivity to the uncertainties of the inlet boundary conditions.…”

Section: Introductionmentioning

confidence: 99%

Effect of a pressure-equalizing film on the trajectory and attitude robustness of an underwater vehicle considering the uncertainty of the platform velocity

Chen

et al. 2018

Engineering Applications of Computational Fluid Mechanics

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A vertically moving underwater vehicle with an air film attached to its exterior can significantly weaken the hydrodynamic disturbances caused by launch conditions. To quantify the ability of a pressure-equalizing film to improve the trajectory and attitude robustness of vehicles under an uncertain platform velocity input, the response surface model of nonintrusive polynomial chaos was built based on sample spacing constructed with a nested sparse grid-based stochastic collocation method. The results indicate the uncertainty bars of the horizontal displacement exhibit an expanding-contracting-expanding pattern with a 'spindle' shape as the vehicle moves. In contrast, the horizontal velocity presents an 'hourglass' shape. Additionally, the horizontal velocity and the pitching angular velocity of the vehicle are quite sensitive to the uncertainty of the platform velocity, and the large mean value and uncertainty of these factors will statistically worsen the trajectory and attitude of the vehicle. Implementation of an exhaust during the water-emerging process can weaken the horizontal motion and pitching rotation of a vehicle, as well as the relevant uncertainty. This is attributed to a generated pressure-equalizing region with a low uncertainty. Thus, an exhaust is urgently needed in the water-emerging process of these vehicles.

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Section: Introductionmentioning

confidence: 99%

Effect of a pressure-equalizing film on the trajectory and attitude robustness of an underwater vehicle considering the uncertainty of the platform velocity

Chen

et al. 2018

Engineering Applications of Computational Fluid Mechanics

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“…This stiff mechanical relaxation has been widely investigated in [3,4,1] and many more. The following paper treats a five equation reduced model, as also many contributions as [1,4,5,6,7,8,9,10] do. This system originates from Kapila et al [11], where they take the formal limit [12] of the Baer and Nunziato seven equation model when the relaxation parameters tend simultaneously to infinity, and thus permitting to assume a single pressure and velocity.…”

Section: Introductionmentioning

confidence: 99%

Hybrid Explicit Residual Distribution Scheme for Compressible Multiphase Flows

Bacigaluppi

Abgrall

Kaman

2017

J. Phys.: Conf. Ser.

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. With respect to other contributions in that area, we investigate a method that provides mesh convergence to the exact solutions, where the studied non-conservative system is associated to consistent jump relations. The adopted scheme consists of a coupled predictor-corrector scheme, which follows the concept of residual distributions in Ricchiuto and Abgrall (J. Comp. Physics 2010), with a classical Glimm's scheme (J. Sci. Stat. Comp. 1982) applied to the area where a shock is occurring. This numerical methodology can be easily extended to unstructured meshes. Test cases on a perfect gas for a two phase compressible flow on a Riemann problem have verified that the approximation converges to its exact solution. The results have been compared with the pure Glimm's scheme and the expected exact solution, finding a good overlap.

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Numerical Investigation of Trajectory and Attitude Robustness of an Underwater Vehicle Considering the Uncertainty of Platform Velocity and Yaw Angle

Chen

et al. 2018

Journal of Fluids Engineering

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The vertically launched underwater vehicle always suffers various hydrodynamic disturbances in its water-emerging process due to the uncertainty of the launch platform motion. Based on the nested sparse grid based stochastic collocation method (NSSCM) and nonintrusive polynomial chaos method, the effect of uncertainty of platform velocity and yaw angle on robustness of vehicle's trajectory and attitude is numerically studied. Results indicate that the uncertainty stemming from platform motion propagates along vehicle's water-emerging process. As the negative horizontal velocity of vehicle gradually changes to positive direction, the uncertainty bar of horizontal velocity presents contracting-expanding mode with an “hourglass” shape while the uncertainty bar of horizontal displacement experiences a “spindle-shaped” one (expanding-contracting-expanding), which is a half cycle later compared with the velocity. The uncertain motion of platform enlarges the uncertainty bar of bottom force via its impact on the gas-leakage process of trail bubble, resulting in the increasing of uncertainty of vertical velocity. Pitching angle (attitude of vehicle) and pitching angular velocity of vehicle persist getting worse driven by the pressure difference between vehicle's front and back sides especially on head part. And their continuous increasing uncertainty bars are formed mainly due to the condition that pressure uncertainty of front side is larger than that on back side, which also leads to the increasing of uncertainty of horizontal force.

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Numerical simulation of cavitating flows under uncertainty

Cited by 3 publications

References 21 publications

Effect of a pressure-equalizing film on the trajectory and attitude robustness of an underwater vehicle considering the uncertainty of the platform velocity

Effect of a pressure-equalizing film on the trajectory and attitude robustness of an underwater vehicle considering the uncertainty of the platform velocity

Hybrid Explicit Residual Distribution Scheme for Compressible Multiphase Flows

Numerical Investigation of Trajectory and Attitude Robustness of an Underwater Vehicle Considering the Uncertainty of Platform Velocity and Yaw Angle

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