Modeling rarefied gas chemistry with QuiPS, a novel quasi-particle method

Poondla, Yasvanth; Goldstein, David; Varghese, Philip L.; Clarke, Peter; Moore, Christopher

doi:10.1007/s00162-021-00598-4

Cited by 2 publications

(7 citation statements)

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“…Four publications discuss state-of-the-art kinetic theory methods which resolve shock layers and permit unraveling the internal shock structure. A novel Boltzmann solution method, denominated quasi-particle simulation (QuiPS), is presented by Poondla, Goldstein, Varghese, Clarke and Moore [45], who implemented chemistry for five-species air and demonstrated efficient recovery of results at re-entry conditions. Compared to classic Direct Simulation Monte Carlo (DSMC) methods, QuiPS is reported to reduce the noise inherent to particle simulations, although results have only been discussed at near chemical equilibrium rarefied flow conditions.…”

Section: Summary Of Articles In This Special Issuementioning

confidence: 99%

Special issue on the fluid mechanics of hypersonic flight

Theofilis

Pirozzoli

Martin

2022

Theor. Comput. Fluid Dyn.

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Flow phenomena on maneuverable vehicles that fly at hypersonic speeds and altitudes that reach the Earth's upper stratosphere and lower mesosphere pose challenges that collectively form one of the present-day research frontiers of Fluid Mechanics. Research agencies around the world have realized the multiple benefits derived from transitioning a deeper understanding of hypersonic flow phenomena to actual flying platforms, and support for hypersonic research has increased substantially in the last decade. The result can be seen in Fig. 1, showing the distribution over years and originating countries of a total of 26,300 peer-reviewed research papers that have been published since the word hypersonic first appeared in the literature in the early 1940s and have this word in their title. Early peak activity subsided after the Moon landing, but soon picked up in the early 80s and again around the turn of the century, growing monotonically to the present day. As also shown in Fig. 1, a breakdown by country of origin reveals that two-thirds of the total number of hypersonic publications originate from the USA and China, giving rise to concerns raised by strategic think-tanks [57] and policy advisers [61] regarding potential misuse of hypersonic technology.Hypersonic research has not always come to the limelight on account of potential strategic conflicts. The high plateau in number of papers published around the 1990s, shown in the left plate of Fig. 1, corresponds to intense activity that took place on the crest of the success of the early Space Shuttle flights, relating to the new Orient Express [47] of hypersonic travel. Large (and largely drawing board) projects involving substantial research into hypersonic flow physics, namely the National Aerospace Plane in the USA, Buran in the final years of the Soviet Union, HOTOL in the UK, Hermes in France and Sänger in Germany, alongside lower-scale efforts in India and Brazil, all testified to a time of optimism regarding hypersonic travel in a civilian transport V. Theofilis

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Section: Summary Of Articles In This Special Issuementioning

confidence: 99%

Special issue on the fluid mechanics of hypersonic flight

Theofilis

Pirozzoli

Martin

2022

Theor. Comput. Fluid Dyn.

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“…In the present work, the remapping procedure developed in [43,44,19], and later extended to non-uniform velocity grids [21], is used. It allows for easy incorporation of internal energy transitions [21], chemical reactions [45,22] and anisotropic scattering laws [24]. Here, a brief overview of the remapping procedure is given for points lying inside the domain bounded by D; for a more detailed description, including the treatment of velocities that fall outside of the domain bounded by D and generalization to non-uniform grids, the reader is referred to [21].…”

Section: Collisionsmentioning

confidence: 99%

Section: Collisionsmentioning

confidence: 99%

“…As in [22], the value of N c is computed taking into account the minimum value of the equilibrium distribution function on the defined grid (via the presence of the exp mv 2 max 2kT α factor). However, in [22], α was taken to be 1. Assuming a fixed velocity grid with a v max = √ 3 × 3.5 2kT ref /m (which corresponds to the maximum speed on a cubic grid with an extent of ±3.5 2kT ref /m (here T ref is some fixed reference temperature), a 2-fold increase in T (compared to the reference temperature T ref ) leads to an approximately 2×10 7 -fold reduction in N c .…”

Section: Collisionsmentioning

confidence: 99%

“…Despite these drawbacks of the linear models, they offer advantages in terms of being scalable to dense regimes [16,17].Another subfamily of the discrete velocity methods does not resort to substituting the collision operator with a simplified model relaxation term, and instead models the full collision process, utilizing remapping procedures to re-distribute post-collisional mass onto the discrete velocity grid [18,19]. These approaches have been shown to be capable of simulating more complex collisional processes, such as internal energy relaxation [20,21], chemical reactions [22], and ionization [23,24], and can make use of state-specific cross-sections and anisotropic scattering laws.…”

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Modeling of Ionized Gas Flows with a Velocity-space Hybrid Boltzmann Solver

Oblapenko

Goldstein

Varghese

et al. 2021

AIAA Scitech 2021 Forum

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In the present work, the Tensor-Train decomposition algorithm is applied to reduce the memory footprint of a stochastic discrete velocity solver for rarefied gas dynamics simulation. An energyconserving modification to the algorithm is proposed, along with an interleaved collision/convection routine which allows for easy application of higher-order convection schemes. The performance of the developed algorithm is analyzed for several 0-and 1-dimensional model problems in terms of solution error and reduction in memory use requirements.Keywords Boltzmann equation • discrete velocity method • tensor decomposition • tensor train • rarefied gas • low-rank approximation IntroductionThe motion of gas or fluid can be successfully described by a set of partial different equations under a wide range of conditions of interest. However, in rarefied regimes, when the ratio of the molecular mean free path to the characteristic length scale becomes large, the continuum approaches no longer apply, and instead, the full Boltzmann equation describing the evolution of the velocity distribution function due to advection, external forces, and collisions, has to be solved. It is a complicated integro-differential equation, with a 6-dimensional integral (the collision operator) appearing on the right-hand side. Numerous approaches have been developed over the years to tackle the equation. These include stochastic approaches, such as the Direct Simulation Monte Carlo (DSMC) method [1], and deterministic approaches, such as discrete velocity methods [2] and spectral methods [3,4].The family of discrete velocity methods (DVM), which is the main focus of the present work, operates by discretizing the velocity distribution function on a grid in velocity space, and obtains a system of partial differential equations for the values of the distribution function at each grid node. A significant advantage offered by discrete velocity methods is the noticeable reduction in noise compared to particle-based methods, which is needed to better understand the small time-scale dynamics of complex rarefied flows, especially in unsteady scenarios [5,6,7].Within the discrete velocity framework, the complex collision operator is often replaced with a simple relaxation term [8,9]. Such relaxation terms include the Bhatnagar-Gross-Krook (BGK) model [10] and its extensions, the ellipsoidal-statistical BGK model (ES-BGK) [11] and the Shakhov model (S-model) [12]. However, the correct incorporation of complex collisional physical phenomena, such as chemical reactions, transitions of internal energy, and complicated scattering laws within the framework of these model equations is still an open question and a topic of active research [13,14,15]. Despite these drawbacks of the linear models, they offer advantages in terms of being scalable to dense regimes [16,17].Another subfamily of the discrete velocity methods does not resort to substituting the collision operator with a simplified model relaxation term, and instead models the full collision process, utilizing...

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Modeling rarefied gas chemistry with QuiPS, a novel quasi-particle method

Cited by 2 publications

References 25 publications

Special issue on the fluid mechanics of hypersonic flight

Special issue on the fluid mechanics of hypersonic flight

Modeling of Ionized Gas Flows with a Velocity-space Hybrid Boltzmann Solver

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