An application of the meshless Local Radial Basis Function Collocation Method(LRBFCM)[22,30–33]in solution of incompressible turbulent combined forced and natural convection is for the first time explored in the pres...An application of the meshless Local Radial Basis Function Collocation Method(LRBFCM)[22,30–33]in solution of incompressible turbulent combined forced and natural convection is for the first time explored in the present paper.The turbulent flow equations are described by the low-Re number k−εmodel with Launder and Sharma[23]and Abe et al.[1]closure coefficients.The involved temperature,velocity,pressure,turbulent kinetic energy and dissipation fields are represented on overlapping 5-noded sub-domains through the collocation by using multiquadrics Radial Basis Functions(RBF).The involved first and second order partial derivatives of the fields are calculated from the respective derivatives of the RBF’s.The involved equations are solved through the explicit time stepping.The pressure-velocity coupling is based on Chorin’s fractional step method[11].The adaptive upwinding technique,proposed by Lin and Atluri[27],is used because of the convection dominated situation.The solution procedure is represented for a 2D upward channel flow with differentially heated walls.The results have been assessed by achieving a reasonable agreement with the direct numerical simulation of Kasagi and Nishimura[20]for Reynolds number 4494,based on the channel width,and Grashof number 9.6×105.The advantages of the represented mesh-free approach are its simplicity,accuracy,similar coding in 2D and 3D,and straightforward applicability in non-uniform node arrangements.展开更多
Liquid micro-jets, produced from gas dynamic virtual nozzles (GDVNs), are used as sample carriers for interaction with X-ray beam in serial femtosecond crystallography (SFX). A numerical investigation of the effect of...Liquid micro-jets, produced from gas dynamic virtual nozzles (GDVNs), are used as sample carriers for interaction with X-ray beam in serial femtosecond crystallography (SFX). A numerical investigation of the effect of the focusing gas type on the liquid micro-jet properties (its length and thickness) is presented. The study complements our previous research on the influence of operating conditions and the nozzle geometry on GDVN performance. The influence of helium, argon, carbon dioxide and nitrogen gases (at a fixed mass flow rate of 1.6 × 104 mg/min) on focusing pure water jet (flow rate of 33 μl/min) is analysed.展开更多
基金The authors would like to express their gratitude to Slovenian Technology Agency for support in the framework of the project Young Researcher from Economy,operation partly financed by the European UnionEuropean Social Fund(RV)Slovenian Research Agency for funding in the framework of the project J2-0099 Multiscale Modeling of Liquid-Solid Systems(BS).
文摘An application of the meshless Local Radial Basis Function Collocation Method(LRBFCM)[22,30–33]in solution of incompressible turbulent combined forced and natural convection is for the first time explored in the present paper.The turbulent flow equations are described by the low-Re number k−εmodel with Launder and Sharma[23]and Abe et al.[1]closure coefficients.The involved temperature,velocity,pressure,turbulent kinetic energy and dissipation fields are represented on overlapping 5-noded sub-domains through the collocation by using multiquadrics Radial Basis Functions(RBF).The involved first and second order partial derivatives of the fields are calculated from the respective derivatives of the RBF’s.The involved equations are solved through the explicit time stepping.The pressure-velocity coupling is based on Chorin’s fractional step method[11].The adaptive upwinding technique,proposed by Lin and Atluri[27],is used because of the convection dominated situation.The solution procedure is represented for a 2D upward channel flow with differentially heated walls.The results have been assessed by achieving a reasonable agreement with the direct numerical simulation of Kasagi and Nishimura[20]for Reynolds number 4494,based on the channel width,and Grashof number 9.6×105.The advantages of the represented mesh-free approach are its simplicity,accuracy,similar coding in 2D and 3D,and straightforward applicability in non-uniform node arrangements.
文摘Liquid micro-jets, produced from gas dynamic virtual nozzles (GDVNs), are used as sample carriers for interaction with X-ray beam in serial femtosecond crystallography (SFX). A numerical investigation of the effect of the focusing gas type on the liquid micro-jet properties (its length and thickness) is presented. The study complements our previous research on the influence of operating conditions and the nozzle geometry on GDVN performance. The influence of helium, argon, carbon dioxide and nitrogen gases (at a fixed mass flow rate of 1.6 × 104 mg/min) on focusing pure water jet (flow rate of 33 μl/min) is analysed.
