Consistent discretization for simulations of flows with moving generalized curvilinear coordinates

We develop a consistent discretization of conservative momentum and scalar transport for the numerical simulation of flow using a generalized moving curvilinear coordinate system. The formulation guarantees consistency between the discrete transport equation and the discrete mass conservation equation due to grid motion. This enables simulation of conservative transport using generalized curvilinear grids that move arbitrarily in three dimensions while maintaining the desired properties of the discrete transport equation on a stationary grid, such as constancy, conservation, and monotonicity. In addition to guaranteeing consistency for momentum and scalar transport, the formulation ensures geometric conservation and maintains the desired high‐order time accuracy of the discretization on a moving grid. Through numerical examples we show that, when the computation is carried out on a moving grid, consistency between the discretized scalar advection equation and the discretized equation for flow mass conservation due to grid motion is required in order to obtain stable and accurate results. We also demonstrate that significant errors can result when non‐consistent discretizations are employed. Copyright © 2009 John Wiley & Sons, Ltd.     

CWC映射和度量化定理

利用CWC映射,本文获得了对称度量空间和g可度量空间的特征,建立了几个度量化定理,改进了一些已知结果．主要的定理是证明正则空间X是可度量化空间当且仅当存在X上的CWC映射g满足如下条件: (Ⅰ)若序列{xn}和{yn}对于每一n∈N有xn∈g(n,yn)且xn→x,则yn→x．(Ⅱ)若序列{xn}和{yn}对于每一n∈N有yn∈g(n,yn)且xn→x,则yn→x．     

Microsynthesis and electron ionisation mass spectrometric analysis of chemical weapons convention (CWC)-related O,O-dialkyl-N,N-dialkylphosphoramidates

The paper describes microsynthesis and GC/EIMS analysis of O,O-dialkyl-N,N-dialkylphosphoramidates (DADAPs). DADAPs belong to schedule 2B6 category of chemical weapons convention (CWC), as they are important markers of the chemical warfare agent Tabun and its analogues. The study was undertaken to develop a spectral database of DADAPs for verification of CWC. The reported synthetic strategy can be adopted to prepare several analogues of DADAPs simultaneously and rapidly during official proficiency tests, for the unambiguous identification of analytes within a short period. Based on the EIMS data of more than 60 compounds, fragmentation routes are proposed which explain the formation of most of the characteristic fragment ions. Subtle differences in EIMS of isomeric DADAPs are discussed to facilitate their identification.     

An efficient method for the esterification of phosphonic and phosphoric acids using silica chloride

Silica chloride is used as an effective heterogeneous catalyst for the rapid esterification of alkyl/aryl phosphonic/phosphoric acids to their corresponding alkyl/aryl phosphonates/phosphates under mild conditions with quantitative yields.