COMSOLMultiphysics中各常用内置参量.doc

Summary of Built-In Variables With Reserved Names This section is an overview of the built-in elements of the following categories as defined by the underlying COMSOL language: ? Constants ? Variables ? Functions These language elements are built-in or user-defined. In addition there are operators that cannot be user-defined, and expressions, which are always user-defined. 具有保留名称的内置变量摘要 本节概述了由基础COMSOL语言定义的以下类别的内置元素： ?常量?变量?功能 这些语言元素是内置的或用户定义的。 此外，还有不能由用户定义的运算符，以及始终由用户定义的表达式。 About Reserved Names关于预留名称 Built-in variables have reserved names, names that cannot be redefined by the user. It is not recommended to use a reserved variable name for a user-defined variable, parameter, or function. For some of the most common reserved variable names, such as pi, i, and j, the text where you enter the name turns orange and you get a tooltip message if you select the text string. Reserved function names are reserved only for function names, which means that such names can be used for variable and parameter names, and vice versa. The following tables list most built-in elements and hence those reserved names. 内置变量具有保留名称，用户无法重新定义。 不建议对用户定义的变量，参数或函数使用保留的变量名。 对于一些最常见的保留变量名称，例如pi，i和j，输入名称变为橙色，如果选择文本字符串，则会得到工具提示消息。 保留的函数名称仅作为函数名保留，这意味着此类名称可用于变量和参数名称，反之亦然。 下表列出了大多数内置元素，因此列出了这些保留名称。 Constants and Parameters常量和参数 There are three different types of constants: built-in mathematical and numerical constants, built-in physical constants, and parameters. Parameters are user-defined constants that can vary over parameter sweeps. Constants are scalar valued. The following table lists the built-in physical constants. Constants and parameters can have units. 有三种不同类型的常数：内置的数学和数值常数，内置的物理常数和参数。 参数是用户定义的常量，可以随参数扫描而变化。 常量是标量值。 下表列出了内置物理常量。 常量和参数可以有单位。 Built-in Physical Constants内置物理常数 Table 5-12: Built-in Physical Constants Name Description描述 g_const Acceleration of gravity N_A_const Avogadro constant k_B_const Boltzmann constant Z0_const Characteristic impedance of vacuum (impedance of free