boltzmann number 中文意思是什麼
boltzmann number
解釋
波爾茲曼數-
Secondllv in the 1 d random traffic flow model. the relation function between the correlation and the creation. disappearance. brake probabilities of the vehicles is presented. according to the statistical mechanical approach to the spatial correlation functions. the theoretical results agree with that of the computer simulation. thirdh. based on the bml model. a main - road traffic flow model with two speeds on two dimensions is designed. this model simulate the traffic situation of one main road and several branches in the cit traffic lights placed on the crossing. vehicles breaking ~ vhile running and turning to other direction while jamming. we investigate the ~ ' e1ocitv and flo ~ ~ of the model when the initial densitvthe brake and turning probabilities. the green to signal rati3. thc number of the branches and the period of the signal are changed. then the reasons causing all the kinds of phenomena are analvzed. finallv. we simulate the bml model using the method of lattice boltzmann which ~ vas brought out by liu mu - renand obtain the velocity - density graph similar to the previous result. the upper critical densiw above which there are oniv jamming configurations. and the lo ~ ver critical density below which there are only moving configurations are the same as before. the boltzmann function which is on the lattices shows the moving and jaxmning transition obviouslv. thus it proves the possibilit of this method on the traffic research
接著，建立了和研究了二維二速的主幹道模型，該模型模擬了城市交通中一條主幹道，多條支道的交通情況，在幹道與支道的交叉路口設置紅綠燈，車輛在運行中可以有對突發事件發生反應的剎車，在發生堵塞時，路口的車輛可考慮通過轉向來緩解交通等各種實際情況的發生，給出了車輛演化的演化方程，並通過計算機模擬，研究模型在改變車輛的初始密度、剎車概率、轉向概率、支道數、紅綠燈信號的綠信比、紅綠燈信號周期等各種情況下支、主幹道車輛的速度、流量的變化，並分析在各種情況下交通狀況的成因，提出改善交通的有效措施。最後，在劉慕仁提出的用格子boltzmann方法研究一維決定論交通流的思路下，將此法推廣到對二維bml模型的模擬上，得到了與用以往方法的研究結果相類似的速度-密度圖線，且車輛從運動相到堵塞相轉變的上下臨界密度是一致的，同時分別給出車輛在處于暢通相和堵塞相時， boltzmann函數在格子上的分佈情況，進一步驗證了此法的可行性。 -
Numerical stability, the other issue of the lattice boltzmann method, is discussed in chapter 5. corresponding to the uniform and shear background flow, the stability of d2q7 d2q9 and d3ql5 model is analyzed through the von neumann linear stability theory, both the conclusion about the mass distribution parameters, the wave number, the relaxation time and the uniform velocity, and the linear stability criterion n r0. 58 are instructive to numerical simulation of flow
第五章考慮了數值方法另外一個方面的問題，在均勻流和剪切流兩種背景流場下，運用vonneumann線性分析法，針對d2q7 、 d2q9及d3q15格子模型，分析了質量分佈參數、波數、鬆弛時間和平均流速等決定模型穩定性的主要參數對模型穩定性的影響，得到了對流場數值計算具有指導意義的一般性結論與線性穩定性標準n r _ e ~ （ 0 . 58 ） 。 -
According to the mathematic modeling principle of physical problem, the error of lattice boltzmann model is analyzed in chapter 3. the nonlinear deviation term from the navier - stokes equation is given, and the main model coefficients, such as speed of sound, viscosity and so on, are verified by numerical computation, the results show that the lattice boltzmann method has second order precision in space and in time which satisfy the engineering application, whereas, the compressible effect ca n ' t be neglected along with mach number increasing, and must be reduced or eliminated
其次，按照物理問題數學建模的原則，對格子法的誤差進行了分析，給出了格子bgk方程再現navier - stokes方程時的壓縮誤差項，並數值驗證了格子模型的聲速及粘性系數等相關參數的精度，表明格子模型盡管具有時空二階精度，能滿足工程計算的要求，但隨著mach數增大，壓縮誤差逐漸成為主要誤差，必須予以消除。
分享友人