MULTIGRAIN: A smoothed particle hydrodynamics algorithm for multiple small dust grains and gas

A smoothed particle hydrodynamics algorithm for multigrain dust with separate sets of particles

We present a method for simulating the dynamics of a mixture of gas and multiple species of large Stokes number dust grains, typical of evolved protoplanetary discs and debris discs. The method improves upon earlier methods, in which only a single grain size could be represented, by capturing the differential backreaction of multiple dust species on the gas. This effect is greater for large dust-to-gas ratios that may be expected in the later stages of the protoplanetary disc life. We benchmark the method against analytic solutions for linear waves, drag and shocks in dust-gas mixtures, and ra…

MULTIGRAIN: Simulating mixtures of multiple dust grains and gas with SPH

We present MULTIGRAIN, an algorithm for simulating multiple phases of small dust grains embedded in a gas, building on our earlier work in simulating two-phase mixtures of gas and dust in SPH (Laibe & Price 2012a,b; Price & Laibe 2015). The MULTIGRAIN method (Hutchison, Price & Laibe 2018) is more accurate than single-phase simulations because the gas experiences a backreaction from each dust phase and communicates this change to the other phases, thereby indirectly coupling the dust phases together. The MULTIGRAIN method is fast, explicit and low storage, requiring only an array of dust fract…

一种用光滑粒子流体动力学模拟小尘埃颗粒动力学的隐式算法

An implicit algorithm for simulating the dynamics of small dust grains with smoothed particle hydrodynamics

本研究提出一种用于光滑粒子流体动力学的隐式算法，求解终端速度近似下小尘埃占比的扩散方程，通过解析求解三次方程实现，避免了显式方法的负值问题，降低了计算成本，但仍不适用于大颗粒场景。

A fast and explicit algorithm for simulating the dynamics of small dust grains with smoothed particle hydrodynamics

We describe a simple method for simulating the dynamics of small grains in a dusty gas, relevant to micron-sized grains in the interstellar medium and grains of centimetre size and smaller in protoplanetary discs. The method involves solving one extra diffusion equation for the dust fraction in addition to the usual equations of hydrodynamics. This "diffusion approximation for dust" is valid when the dust stopping time is smaller than the computational timestep. We present a numerical implementation using Smoothed Particle Hydrodynamics (SPH) that is conservative, accurate and fast. It does no…

SPH中多尘埃物种的全单流体含尘气体

Full one-fluid dusty gas with multiple grain species in SPH

提出SPH中多尘埃物种的全单流体算法，推广终端速度近似以处理任意阻力机制，通过测试验证其准确性，并指出对较大颗粒（Stokes数≥1）终端速度近似误差显著，全单流体方法更优。

Two phase mixtures in SPH - A new approach

We present a new approach to simulating mixtures of gas and dust in smoothed particle hydrodynamics (SPH). We show how the two-fluid equations can be rewritten to describe a single-fluid 'mixture' moving with the barycentric velocity, with each particle carrying a dust fraction. We show how this formulation can be implemented in SPH while preserving the conservation properties (i.e. conservation of mass of each phase, momentum and energy). We also show that the method solves two key issues with the two fluid approach: it avoids over-damping of the mixture when the drag is strong and prevents a…