对流和扩散之间有什么区别

这对流和扩散之间的关键区别是，对流是大量粒子通过流体沿相同方向的大运动，而扩散是单个颗粒的运动和粒子的转移动力和能量到流体中的其他颗粒。

Convection and diffusion are two physical processes we can describe chemically through the movement of particles.

内容

1。概述和关键差异
2。什么是对流
3。什么是扩散
4。对流与表格形式的扩散
5。摘要 - 对流与扩散

什么是对流?

对流是传播热量through the bulk movement of molecules within fluids. The fluid can be either a gas or a liquid. Initially, the heat transfer between the fluid and an object occurs through conduction; however, the bulk heat transfer occurs due to the motion of the fluid. We can simply say convection is the heat transfer process in fluids through the actual motion of matter. This process can occur as a natural or a forced process.

Concerning the process of convection, heating a fluid causes thermal expansion, and the layers which are closest to the heating source gets hotter and become less dense. Thus, followed by this is the rising up of the hotter part of the fluid according to buoyancy where the colder fluid layers tend to replace the rising hot fluid layers. This process repeats, and it is the process of convection where heat transfer occurs.

有两种形式的对流作为自然对流和强迫对流。自然对流是由于浮力，并且由于外部来源（例如风扇或泵的风）而发生强制对流。

什么是扩散?

扩散是通过浓度梯度从高浓度到低浓度的分子的运动。这些运动发生在相同的解决方案中。影响浓度梯度的因素也会影响扩散。

在扩散中，当两个区域的浓度在每个点相等时，该运动就会终止。这意味着这种运动发生在浓度梯度消失之前。然后分子在溶液内部散布。

分子的运动速度diffusion is a function of temperature, the viscosity of the gas (or fluid) and particle size. Usually, molecular diffusion describes the net flux of molecules from a region of high concentration to a low concentration. When considering the two systems, A1 and A2, which are at the same temperature and are capable of exchanging molecules between them, a change in the势能在这两个系统中，这两个系统都可以创建从一个系统到另一个系统（从A1到A2，反之亦然）的能量流。这是因为任何系统自然都更喜欢低能和高熵状态。这会产生分子扩散状态。

对流和扩散有什么区别？

对流和扩散是我们可以通过颗粒运动来化学描述的物理过程。对流和扩散之间的关键区别在于，对流是大量粒子通过流体向对流的大量运动，而扩散是单个颗粒的运动以及粒子的动量和能量转移到流体中的其他颗粒。

以下信息图列出了对流和扩散在表格形式中的差异，以与并排比较。

摘要 - 对流与扩散

对流是通过流体中分子的批量运动传热的过程。扩散是通过浓度梯度从高浓度到低浓度的分子的运动。这refore, the key difference between convection and diffusion is that convection is the large movement of a large mass of particles in the same direction through the fluid, whereas diffusion is the movement of single particles and transfer of particle’s momentum and energy to other particles in the fluid.

参考：

1.“”什么是对流？- 定义，类型，示例。”Byjus，2020年9月8日。

图片提供：

1.“”对流单元” contection_cells.png：Theresa Knott（原始），Joanjoc版本，没有文本衍生作品：McSush - 此文件来自：Contection Cells.png：（CC BY-SA 3.0）通过Commons Wikimedia
2.“”Blausen 0315扩散” By BruceBlaus – Own work（CC由3.0）通过Commons Wikimedia