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In this paper we study isentropic flow in a curved pipe. We focus on the consequences of the geometry of the pipe on the dynamics of the flow. More precisely, we present the solution of the general Cauchy problem for isentropic fluid flow…

Analysis of PDEs · Mathematics 2016-11-03 Rinaldo M. Colombo , Helge Holden

A normalizing flow models a complex probability density as an invertible transformation of a simple density. The invertibility means that we can evaluate densities and generate samples from a flow. In practice, autoregressive flow-based…

Machine Learning · Statistics 2019-06-06 Conor Durkan , Artur Bekasov , Iain Murray , George Papamakarios

This paper is concerned with reconstructing an acoustic obstacle and its excitation sources from the phaseless near-field measurements. By supplementing some artificial sources to the inverse scattering system, this co-inversion problem can…

Numerical Analysis · Mathematics 2022-12-20 Deyue Zhang , Yue Wu , Yukun Guo

For a given smooth convex cone in the Euclidean $(n+1)$-space $\mathbb{R}^{n+1}$ which is centered at the origin, we investigate the evolution of strictly mean convex hypersurfaces, which are star-shaped with respect to the center of the…

Differential Geometry · Mathematics 2024-08-16 Ya Gao , Jing Mao

We have investigated the motion characteristics of a movable piston immersed in a one dimensional gas of hard rods by event-oriented molecular dynamics in the absence of thermal noise. Periodic and reflecting boundary conditions are…

Soft Condensed Matter · Physics 2014-09-12 M. Ebrahim Foulaadvand , M. Mehdi Shafiee

We introduce the shifted inverse curvature flow in hyperbolic space. This is a family of hypersurfaces in hyperbolic space expanding by $F^{-p}$ with positive power $p$ for a smooth, symmetric, strictly increasing and $1$-homogeneous…

Differential Geometry · Mathematics 2023-02-03 Xianfeng Wang , Yong Wei , Tailong Zhou

Dynamics of inelastic gases are studied within the framework of random collision processes. The corresponding Boltzmann equation with uniform collision rates is solved analytically for gases, impurities, and mixtures. Generally, the energy…

Statistical Mechanics · Physics 2007-05-23 E. Ben-Naim , P. L. Krapivsky

The structure of shocks that form at the exhaust boundaries during collisionless reconnection of anti-parallel fields is studied using particle-in-cell (PIC) simulations and modeling based on the anisotropic magnetohydrodynamic equations.…

Plasma Physics · Physics 2015-06-03 Yi-Hsin Liu , J. F. Drake , M. Swisdak

We are concerned with the one-dimensional piston problem for the compressible Euler equations of Chaplygin gas. If the piston moves at constant subsonic speed to the uniform gas, there exists an integral weak solution for the piston…

Analysis of PDEs · Mathematics 2019-06-14 Aifang Qu , Hairong Yuan

We analyze the transition between pulled and pushed fronts both analytically and numerically from a model-independent perspective. Based on minimal conceptual assumptions, we show that pushed fronts bifurcate from a branch of pulled fronts…

Analysis of PDEs · Mathematics 2022-06-22 Montie Avery , Matt Holzer , Arnd Scheel

We describe ideal incompressible hydrodynamics on the hyperbolic plane which is an infinite surface of constant negative curvature. We derive equations of motion, general symmetries and conservation laws, and then consider turbulence with…

Chaotic Dynamics · Physics 2015-06-18 Gregory Falkovich , Krzysztof Gawedzki

Control surface deployment in a supersonic flow has many applications, including flow control, mixing, and body-force regulation. The extent of control surface deflections introduces varying flow unsteadiness. The resulting fluid dynamics…

Fluid Dynamics · Physics 2022-10-26 S. K. Karthick , D. Bhelave , A. De

We are concerned with a model describing the motion of two compressible, immiscible fluids with density-dependent viscosity in the whole $\mathbb R^3$. The phases of the flow may have different pressure and viscosity laws and are separated…

Analysis of PDEs · Mathematics 2025-10-14 Marcel Zodji

A streamwise-constant model is presented to investigate the basic mechanisms responsible for the change in mean flow occuring during pipe flow transition. Using a single forced momentum balance equation, we show that the shape of the…

Fluid Dynamics · Physics 2015-05-27 Jean-Loup Bourguignon , Beverley J. McKeon

We analyze the dynamics of a distribution circuit loaded with many induction motor and subjected to sudden changes in voltage at the beginning of the circuit. As opposed to earlier work \cite{13DCB}, the motors are disordered, i.e. the…

Physics and Society · Physics 2015-03-05 Irina Stolbova , Scott Backhaus , Michael Chertkov

We study the inverse problem of reconstructing an incompressible velocity field $\boldsymbol{v}$ from observations of the induced magnetic field $\boldsymbol{b}$. In the presence of a strong, constant background field $\mathbf{F}$, the…

Analysis of PDEs · Mathematics 2026-02-26 Yacine Mokhtari , Christina Frederick , Yunan Yang , Bjorn Engquist

The classical Helmholtz problem is applied for modelling the axisymmetric inviscid cusp-ended separated flow around a sphere. Two coordinate systems are employed: polar for initial calculations and parabolic the latter being more suitable…

Fluid Dynamics · Physics 2007-05-23 M. D. Todorov

Magnetic reconnection in an antiparallel uniform Harris current sheet equilibrium, which is initially perturbed by a region of enhanced resistivity limited in all three dimensions, is investigated through compressible magnetohydrodynamic…

Astrophysics · Physics 2009-10-31 Joerg Schumacher , Bernhard Kliem , Norbert Seehafer

The inverse square potential arises in a variety of different quantum phenomena, yet notoriously it must be handled with care: it suffers from pathologies rooted in the mathematical foundations of quantum mechanics. We show that its…

Soft Condensed Matter · Physics 2015-06-15 Cristiano Nisoli , Alan. R. Bishop

Fluid discontinuities, such as shock fronts and vortex sheets, can reflect waves and become unstable to corrugation. Analytical calculations of these phenomena are tractable in the simplest cases only, while their numerical simulations are…

Plasma Physics · Physics 2023-08-16 William Béthune