Immersed boundary conditions for hypersonic flows using ENO-like least-square reconstruction

Bridel-Bertomeu, Thibault

doi:10.1016/j.compfluid.2020.104794

Cited by 13 publications

(5 citation statements)

References 34 publications

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“…ρ denotes density, u and v denote the x− and y− coordinates of the velocity vector w, E denotes the specific total energy and p denotes the static pressure. The aforementioned mathematical model is described as it is implemented in the in-house code HYPERION (HYPERsonic vehicle design with Immersed bOuNdaries) whose primary capabilities as a massively parallel structured solver using immersed boundary conditions have already been discussed by Bridel-Bertomeu [17]. The present study uses only regular Cartesian grids with constant grid spacings (grid of pixels) in both directions of space, ∆x and ∆y, and will not rely on any immersed boundary condition during the computations presented later.…”

Section: Numerical Simulationmentioning

confidence: 99%

Topological Analysis of Ensembles of Hydrodynamic Turbulent Flows -- An Experimental Study

Nauleau¹,

Vivodtzev²,

Bridel-Bertomeu³

et al. 2022

Preprint

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1: Topological Data Analysis protocols applied on an ensemble dataset of a Kelvin-Helmholtz instability. (a) The 180 members of the ensemble obtained with variations of timesteps, interpolation schemes, orders, resolutions and Riemann solvers (Tab. 1). (b)The top cluster represents the time separation of t 0 and t 1 for the flows S 1 and S 2 with the Wasserstein distance and the bottom cluster with the L 2 -norm. Red lines show the timestep separation with our clustering method whereas the sphere colors are the ground truth, illustrating the limitation of the L 2 -norm. (c) Persistence curve protocol: Differences between integrals of persistence curves (gray area) of the enstrophy computed with a SLAU2 solver, an order 7 TENO scheme and a resolution of 1024 × 1024 for various configurations (S 1 at t 0 , S 2 and S 3 at t 1 ). These integral differences exhibit the appearance of vortices (critical points) as the time increases. (d) Outlier distance protocol: Wasserstein distance matrix for 5 configurations S 1 (t 0 , HLLC), S 2 (t 1 , Roe), S 3 (t 1 , HLLC), S 4 (t 2 , Roe), S 5 (t 2 , HLLC) computed with an order 7 WENO-Z interpolation scheme at 512 × 512. The sum of each row the configuration maximizing this distance between solvers and timesteps, here S 1 . (e) Unsupervised classification: Wasserstein distance matrix for the previous configurations with an order 7 WENO-Z interpolation scheme at 256 × 256. The clustering based on the Wasserstein distance and colored according to the Kmeans clustering method successfully segments the time steps.

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Section: Numerical Simulationmentioning

confidence: 99%

Topological Analysis of Ensembles of Hydrodynamic Turbulent Flows -- An Experimental Study

Nauleau¹,

Vivodtzev²,

Bridel-Bertomeu³

et al. 2022

Preprint

Self Cite

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“…The denoising data is increasing, and the support set is also expanding. After eliminating the noise interference, the least square method [24] is used to reconstruct the original data of children's physical fitness, and its expression is as follows:…”

Section: Threshold Setting and Optimization Algorithmmentioning

confidence: 99%

Evaluation of Children’s Physical Fitness Index and Prediction of Health Risk Trend Based on BP Neural Network Algorithm

Zhang

2022

Wireless Communications and Mobile Computing

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On the basis of literature review and expert interview, this study constructs the indexes of health fitness evaluation, obtains the difference of the indexes before and after the 15-week health fitness intervention, and establishes the health risk trend predictive equation based on BP neural network algorithm. The results of the study are as follows: after 15 weeks of health fitness intervention, there were significant differences in body fat rate, waist circumference, and waist-to-hip ratio ( P < 0.01 ). There were significant differences in maximal oxygen uptake, 12-minute running distance, one-minute sit-ups, push-ups, standing long jump, pull-ups, and sitting forward flexion ( P < 0.05 ). Body fat percentage, maximal oxygen uptake, forward bending in sitting position, and standing long jump can be used to evaluate the level of children’s physical fitness. In conclusion, after 15 weeks of health and fitness intervention course, the children’s health and fitness were improved. Health and Physical Fitness Intervention Curriculum can be promoted in schools so that more children can benefit from it. And the health risk trend prediction model based on BP neural network algorithm has a certain validity.

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“…Predicting aerodynamic heating in supersonic and hypersonic flows is mandatory for the development of aerospace crafts. Due to the high cost of reproducing flight conditions in experiments, the demand for accuracy and speed in computational fluid dynamics (CFD) increases as computational resources increase (Liu and Cao, 2017;Zhao and Li, 2018;Bridel-Bertomeu, 2021;Garbacz et al, 2022). Numerical simulations by boundary-fitted grids are widely used in industrial applications.…”

Section: Introductionmentioning

confidence: 99%

“…In Cartesian grid solvers, the immersed boundary method (Peskin, 1977;Iaccarino and Verzicco, 2003;Mittal and Iaccarino, 2005;Tamaki et al, 2017;Bridel-Bertomeu, 2021) is a popular wall treatment. The shape representation of the immersed boundary method is based on the voxel method.…”

Section: Introductionmentioning

confidence: 99%

Wall heat flux estimation using the Cartesian cut-cell method

TAKEDA,

BABA,

UENO

2023

JFST

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The Cartesian cut-cell method evaluates wall-fluid interactions by using the fluxes through a wall. This wall treatment by the Cartesian cut-cell method is expected to overcome the mass and energy conservation problems of the immersed boundary method. A wall flux evaluation using the image point is proposed in this study to avoid volume center estimation. The Cartesian cut-cell method that uses the proposed wall flux evaluation is validated by the numerical simulations of supersonic flows past simple shapes. In the numerical simulations of the supersonic flow past a cylinder with an isothermal wall, the shorter displacement d IP of the image point from the wall provided a better estimation of the wall heat flux. Furthermore, the wall heat flux distributions and the amount of heat converged with grid refinement. In the numerical simulations of the supersonic flow past a wedge, the minimum grid resolution of the Cartesian cut-cell method for wall flux estimation was suggested. Furthermore, the results of the isothermal wall condition, the adiabatic wall condition, and the inviscid condition were compared.

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Immersed boundary conditions for hypersonic flows using ENO-like least-square reconstruction

Cited by 13 publications

References 34 publications

Topological Analysis of Ensembles of Hydrodynamic Turbulent Flows -- An Experimental Study

Topological Analysis of Ensembles of Hydrodynamic Turbulent Flows -- An Experimental Study

Evaluation of Children’s Physical Fitness Index and Prediction of Health Risk Trend Based on BP Neural Network Algorithm

Wall heat flux estimation using the Cartesian cut-cell method

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