On constraining the smoothed particle hydrodynamics kernel radius in galaxy simulations

	On constraining the smoothed particle hydrodynamics kernel radius in galaxy simulations
	Williams, PR ; Churches, DK ; Nelson, AH
刊名	ASTROPHYSICAL JOURNAL
	2004-05-20
卷号	607 期号:1 页码:1-19
关键词	galaxies : evolution galaxies : formation galaxies : ISM galaxies : structure methods : n-body simulations methods : numerical
英文摘要	In simulations of galaxy formation that use smoothed particle hydrodynamics (SPH) to model the gas component, a lower limit on the value of the kernel smoothing radius h is often imposed, usually equal to the gravitational softening length epsilon. In this paper we analyze a series of benchmark hydrodynamics problems and test galaxy formation simulations, aimed at quantifying the effects of imposing such a constraint on h. We have found that in some circumstances, such an approach can severely degrade the accuracy of solutions. In such cases, using large values of h results in an over-smoothed density field, i.e., a decrease in the calculated values of density rho and density gradients delrho, which unphysically decreases the delrho/rho part of pressure accelerations. In simulations of galaxy disks, constrained h may also result in unphysical angular momentum transfer, affecting the gross structure of the numerical galaxy. Such an effect occurs because particles in the central regions of the disk sample the velocity field in SPH summations over too large a range in velocities. We demonstrate here that when h is allowed to evolve freely to maintain a constant number of neighbors in SPH summations, such unwanted effects can be avoided and accuracy improved. At the same time, significant savings in computational cost can also be made by using the unconstrained h approach.
WOS标题词	Science & Technology ; Physical Sciences
类目[WOS]	Astronomy & Astrophysics
研究领域[WOS]	Astronomy & Astrophysics
关键词[WOS]	HIERARCHICALLY CLUSTERING UNIVERSES ; ANGULAR-MOMENTUM PROBLEM ; DISK GALAXIES ; STAR-FORMATION ; MOLECULAR CLOUDS ; NUMERICAL-SIMULATION ; COSMOLOGICAL CONTEXT ; SUPERNOVA FEEDBACK ; CLUMPS FORMATION ; SPIRAL STRUCTURE
收录类别	SCI
语种	英语
WOS记录号	WOS:000221523900001
内容类型	期刊论文
源URL	[http://119.78.226.72/handle/331011/18325]
专题	上海天文台_星系宇宙学重点实验室
作者单位	1.Chinese Acad Sci, Shanghai Astron Observ, Shanghai 200030, Peoples R China 2.Tohoku Univ, Astron Inst, Aoba Ku, Sendai, Miyagi 9808578, Japan 3.Cardiff Univ, Dept Phys & Astron, Cardiff CF2 3YB, S Glam, Wales
推荐引用方式 GB/T 7714	Williams, PR,Churches, DK,Nelson, AH. On constraining the smoothed particle hydrodynamics kernel radius in galaxy simulations[J]. ASTROPHYSICAL JOURNAL,2004,607(1):1-19.
APA	Williams, PR,Churches, DK,&Nelson, AH.(2004).On constraining the smoothed particle hydrodynamics kernel radius in galaxy simulations.ASTROPHYSICAL JOURNAL,607(1),1-19.
MLA	Williams, PR,et al."On constraining the smoothed particle hydrodynamics kernel radius in galaxy simulations".ASTROPHYSICAL JOURNAL 607.1(2004):1-19.