A novel hybrid DSMC-Fokker Planck algorithm implemented to rarefied gas flows

Mahdavi, Amirmehran; Roohi, Ehsan

doi:10.1016/j.vacuum.2020.109736

Cited by 12 publications

(3 citation statements)

References 26 publications

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“…Other recently suggested promising hybrid methods include the following. Madhavi and Roohi [28] introduced a computationally efficient hybrid approach combining Fokker Planck (FP) and DSMC for simulating rarefied gas flows. It was shown that a modified gradient length Kn had to be considered in defining the accuracy of FP method.…”

Section: Introductionmentioning

confidence: 99%

Feasibility of macroscopic parameters for NS to DSMC solver switching in micronozzle simulations

Kumar M,

Shine

2023

Phys. Scr.

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Enhancing the design and performance of micronozzles could lead to novel applications and advancements in propulsion systems, making the exploration of micronozzles crucial for the future. This paper critically examines the feasibility of utilizing macroscopic property-based Kn as indicator for defining the breakdown region during the transition from the NS solver to the DSMC solver in micronozzle simulations. The aim is to specify a parameter that can be calculated from both NS and DSMC simulations, making it suitable for implementation in hybrid simulations that dynamically switch between the two solvers. The results show that the density-based Kn accurately represents the continuum breakdown, and it exhibits an earlier breakdown compared to pressure and temperature-based Kn values. The study also analyzes the rarefaction effects and introduces the rarefaction parameter (RP), quantifying the increase in Kn for a unit change in the non-dimensionalized distance. The findings demonstrate that at very low exit pressures, the rarefaction effects increase rapidly as the flow moves towards the nozzle exit, leading to a transition from the continuum to the rarefied regime. The hybrid NS-DSMC simulations show good agreement with experimental data, validating the proposed approach. Additionally, the research examines the effect of back pressure on the RP and identifies the transition regime based on the slope of the RP curve. Therefore, the manuscript provides detailed insights into novel elements, such as the quantification of rarefaction within the nozzle using the RP, the classification of the nozzle into different regimes (continuum, slip, and transition), the definition of an easily obtainable parameter for switching between NS and DSMC methods, and an examination of the contributions of the shear stress term and heat addition term to non-equilibrium conditions.

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Section: Introductionmentioning

confidence: 99%

Feasibility of macroscopic parameters for NS to DSMC solver switching in micronozzle simulations

Kumar M,

Shine

2023

Phys. Scr.

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“…For the modelling of flows in rocket nozzles and rarefied exhaust plumes, various approaches have also been implemented in the solution frame of DSMC. An optimised hybrid model of Fokker-Planck (FP) and DSMC aims to provide a lower computational cost by applying the FP method and a higher accuracy from DSMC only where required [21]. The use of DSMC is also extended for the modelling of flow in micro/nanoscale convering-diverging nozzles with the application of unstructured meshes [22] and the simplified Bernoulli trial (SBT) method [23].…”

Section: Introductionmentioning

confidence: 99%

Impact of Stagnation Temperature and Nozzle Configuration on Rarefied Jet Plume Interactions

Agir

White

Kontis

2022

Journal of Spacecraft and Rockets

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“…Managing computational costs while maintaining accuracy is crucial in simulations involving a wide range of local Knudsen numbers or significant variations in local gradients. Various approaches have been explored, including CFD-DSMC hybrid methods [17,[21][22][23] and all-molecular hybrid methods such as DSMC-Equilibrium Particle Simulation Method (EPSM) [24], DSMC-Low Diffusion (LD) [25], DSMC-Dynamic Collision Limiter [26], and DSMC-Fokker-Planck [27][28][29] hybrid methods. These methods address challenges arising from significant variations in local rarefaction, concentrating primarily on the increased computational cost in DSMC simulations with decreasing local Knudsen numbers.…”

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confidence: 99%

Improving computational efficiency in DSMC simulations of vacuum gas dynamics with a fixed number of particles per cell

Sabouri,

Zakeri,

Ebrahimi

2024

Phys. Scr.

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The present study addresses the challenge of enhancing computational efficiency without compromising accuracy in numerical simulations of vacuum gas dynamics using the direct simulation Monte Carlo (DSMC) method. A technique termed “fixed particle per cell (FPPC)” was employed, which enforces a fixed number of simulator particles across all computational cells. The proposed approach eliminates the need for real-time adjustment of particle weights during simulation, reducing calculation time. Using the SPARTA solver, simulations of rarefied gas flow in a micromixer and rarefied supersonic flow around a cylinder were conducted to validate the proposed approach. Results demonstrate that the FPPC concept effectively reduces computational costs while yielding results comparable to conventional DSMC implementations. Additionally, the application of local grid refinement coupled with the FPPC concept is investigated. The results show that integrating local grid refinement with the FPPC concept enables accurate prediction of flow behavior in regions with significant gradients. These findings highlight the efficacy of the proposed approach in improving the accuracy and efficiency of numerical simulations of complex vacuum gas dynamics at a reduced computational cost.

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A novel hybrid DSMC-Fokker Planck algorithm implemented to rarefied gas flows

Cited by 12 publications

References 26 publications

Feasibility of macroscopic parameters for NS to DSMC solver switching in micronozzle simulations

Feasibility of macroscopic parameters for NS to DSMC solver switching in micronozzle simulations

Impact of Stagnation Temperature and Nozzle Configuration on Rarefied Jet Plume Interactions

Improving computational efficiency in DSMC simulations of vacuum gas dynamics with a fixed number of particles per cell

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