Wyniki wyszukiwania - BazTech

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Modelowanie przepływu gazu z uwzględnieniem zderzeń międzycząsteczkowych metodą DSMC

Niewiński M.

Elektronika : konstrukcje, technologie, zastosowania

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2008

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Vol. 49, nr 9

88-92

PL

W pracy omówiono podstawy symulacyjnej metody DSMC - pozwalającej wyznaczyć wybrane parametry makroskopowe przepływu gazu - charakteryzującej się wykorzystaniem metod probabilistycznych do modelowania zderzeń międzycząsteczkowych oraz zderzeń gaz - otoczenie. Ponadto, przedstawiono wstępne wyniki obliczeń symulacyjnych przewodności przewodów cylindrycznych (1 ≤ L/R ≤ 8 gdzie: L - długość, R - promień wlotowy przewodu) w zakresie blisko molekularnego przepływu gazu (dla liczby Knudsena 0,1 ≤ Kn ≤ 0,2). Rezultaty te porównano z wynikami uzyskanymi na drodze analitycznej i dla przewodów długich uzyskano ich zgodność na poziomie 5%.

EN

The paper presents the basic principles of DSMC method which allows to determine the macroscopic parameters of the gas flow. The gas is modelled at microscopic level and the events such as collisions are handled probabilistically. The preliminary results of DSMC simulations were compared with analytical solutions for cylindrical tube conductance (for 1 ≤ L/R ≤ 8 where L - length, R - radius of the tube), and assuming near molecular gas flow regime (for Knudsen number 0.1 ≤ Kn ≤ 0.2). It was found that both results are consistent with 5% for long tubes.

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Analiza wpływu geometrii płytki blokującej komory pompowe na rozkłady gęstości strumienia gazu we wzorcu niskich ciśnień

Niewiński M.

Prace Naukowe Politechniki Warszawskiej. Elektronika

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2005

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z. 153

148-151

EN

This paper presents the results of Monte Carlo computations of gas flux distribution in the chambers of typical calibration system, as a function of two parameters: diameter of bl9ocking plate, placed in pumping chamber and backstream from the pump. It was the backstream from pumping chamber to the calibration chamber depends mainly on diameter of blocking plate, and it significantly increasing with blocking plate`s diameter.

3

Środowisko obliczeń rozproszonych w zastosowaniu do wyznaczania parametrów układów metrologicznych metodą Monte-Carlo

Niewiński M.

Prace Naukowe Politechniki Warszawskiej. Elektronika

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2002

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z. 143

189-192

EN

The paper presents a new approach to an implemantation of the Monte Carlo method for analyses of the high vacuum metrological system based on the dynamic expansion of gas principle. The main disadvantage of the Monte Carlo method, a very long time of computation, was significantly reduced by distributed calculation schema. The paper describes the principles of the system, compares the times of computing for some models of chosen metrological system, performed on many computers.

4

Moly Flow..er Plus : program komputerowy do badania parametrów stanu gazu w układach metrologicznych bardzo wysokiej próżni

Niewiński M., Szwemin P.

Elektronika : konstrukcje, technologie, zastosowania

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2001

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Vol. 42, nr 8-9

91-93

EN

The dynamic expansion of gas is widely used method in the pressure (or the gas number density) standards. The accuracy of the standard depends, among the others, upon the accuracy of calculating the conductance and demands the ununiformities of the gas number density and of the gas flux distributions inside the calibration chamber. Usually during calculation of conductance one assumes the uniform distribution of the molecules at the entrance plane to the orifice system as well as cosine distribution of molecule direction vs. normal to this plane. Many works shows that it is not truth. Moly Flow..er Plus is the software, been development specially for research the parameters of gas flow in metrological systems. It uses Monte-Carlo method for calculating: gas flux distribution and angular distribution inside the calibration chamber and also the time of flight method for conductance of orifice. In this way the chamber shape influence on conductance can be found. Moly Flow..er Plus is full 32-bit program working under Windows 95/98 NT operating system with graphical user interface. In Monte-Carlo simulation, the quality of RNG highly influenced the results of simulation especially if high precision of this process is needed, so there is the possibility to choose Random Number Generator from 5 high quality generators implemented in the program. Program was used in many control application tests connected with comparison the simulation results with the values of Clausing factors for spherical cylindrical and conical elements. All the simulation results were well below 2s interval.

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Przewodność diafragmy wzorcowej - porównanie obliczeń analitycznych i symulacyjnych

Niewiński M., Szwemin P.

Prace Naukowe Politechniki Warszawskiej. Elektronika

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1999

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z. 123

87-92

EN

Different methods of calculating the orifice conductance's correction factor, an important factor for the determining the pressure in dynamic calibration system, have been compared in this paper. This value has been calculated for conductance system recently applied in Instituto di Metrologia Gustavo Colonetti (Italy). Comparison of analytical methods with Monte-Carlo simulations shows that the last method could be successfully use for metrological purposes with uncertainties of the order of 10-5.

6

Program komputerowy Moly Flow..ER dla Windows

Niewiński M., Szwemin P.

Prace Naukowe Politechniki Warszawskiej. Elektronika

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1999

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z. 123

140-146

EN

The new computer program for calculation conductance of composite vacuum system is presented. The uncertainty of the results can be below l O-5. It has been obtained using a random number generator with better properties for longer Monte Carlo simulations. The principles of program have been presented with comparison of the results obtained for two different random number generators. The values of Clausing factors for elementary shapes are also presented for comparison.