# FDDDL

**Repository Path**: gravifer/FDDDL

## Basic Information

- **Project Name**: FDDDL
- **Description**: No description available
- **Primary Language**: Unknown
- **License**: MIT
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2020-06-19
- **Last Updated**: 2020-12-19

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

# 流体大作业

## 湍流

### 转捩前

- Stokes波

	- 处理框架

		- GLM

			- 非线性方程

				- Korteweg–de Vries equation — describes the forward propagation of weakly nonlinear and dispersive waves, for long waves with λ > 7 h.
				- Shallow water equations — are also nonlinear and do have amplitude dispersion, but no frequency dispersion; they are valid for very long waves, λ > 20 h.
				- Boussinesq equations — have the same range of validity as the KdV equation (in their classical form), but allow for wave propagation in arbitrary directions, so not only forward-propagating waves. The drawback is that the Boussinesq equations are often more difficult to solve than the KdV equation; and in many applications wave reflections are small and may be neglected.
				- Airy wave theory — has full frequency dispersion, so valid for arbitrary depth and wavelength, but is a linear theory without amplitude dispersion, limited to low-amplitude waves.
				- Stokes' wave theory — a perturbation-series approach to the description of weakly nonlinear and dispersive waves, especially successful in deeper water for relative short wavelengths, as compared to the water depth. However, for long waves the Boussinesq approach—as also applied in the KdV equation—is often preferred. This is because in shallow water the Stokes' perturbation series needs many terms before convergence towards the solution, due to the peaked crests and long flat troughs of the nonlinear waves. While the KdV or Boussinesq models give good approximations for these long nonlinear waves.

			- 原工作

			- 波作用量 | 浸渐不变量

		- Stokes 边值问题

	- 形式

		- 3阶深水波

			- Deduction

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		- 
		- 五阶形式（工程用）

	- Stokes Drift

		- 推导

- Airy波 | 线性波理论

### 转捩过程

- 调制不稳定性 | 表面波

	- Benjamin−Feir 不稳定性 | 重力波

		- 原工作

			- 原因：反常群速度色散
			- Coarse Analysis

				- Side-band

					- Dispersion relation

						- cannot be satisfied with constant frequencies
						- Slow-varying argument

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					- Nonlinear coupling between side-band & base

						- resonance → growth
						- Dispersion detunes the prospective resonance between second-harmonic components of the basic wave motion and the side-band modes

			- Instable condition

		- Fermi–Pasta–Ulam 重现

		- 二维情况

	- 临界点 | Ligfhthill Criterion

		- wave steepness

	- 控制方程：非线性薛定谔

- Cross-wave 不稳定性 | 表面张力引起

	- 观察方法 FS-SS

		- 教程

		- 应用

	- 完全淹没起振器的实验和理论

- 涡生成

	- Rayleigh-Taylor 不稳定性

	- Kelvin-HelmhoItz 不稳定性

### 转捩后

- 实验现象

	- 整体运动模式
	- 湍流的判据

- 二维湍流

	- 湍流的发展
	- 局部质点运动解释
	- 整体运动模式解释

## 参考

### 湍流统计

- 关联函数
- 谱的物理意义
- 湍动能方程
- 各向同性湍流假设与推论
- Kolmogorov假设

	- 尺度分析
	- energy cascade

- 二维湍流

	- 涡量守恒
	- 反向能量输运

- Taylor扩散理论

### 法拉第波

- 理论

	- 参变共振

		- 

			- 假设

				- 

			- Mathieu方程的条件

	- 子主题 2

- 子主题 2

### 原工作

- 预印本

	- 特点

		- 对长波(重力波)和短波(表面力波)都有效

			- 大尺度结构相同

		- 提高黏度可抑制涡结构

			- 加入蔗糖

		- 运动不同于Stokes Drift

	- tractor beam formation in nonlinear wave regime

		- modulation instability of the finite-­amplitude waves

			- onset of the cross-­wave

		- spatially periodic outward jets in the near field

			- sustain stationary counter-­‐rotating vortices

		- vortex-transportation interaction

			- jet-­driven vortices
			- onset of a region of stochastic Lagrangian transport

		- stochastic pumping of fluid parcels out of the turbulent region
		- generation of the large-­scale vortex pattern with an inward return flow

- 发表本

- 前置工作

### FAST

## 实验

## 报告

## 演示