- Feb 21 2022
- molinaripaol89

Good evening.

Having to simulate a debris flow, which criteria must be considered to best set the resistance coefficient (default = 72)? What is the range of values it can take in a real cases? I have read the information provided in the manual and in the article “Numerical Simulation of a Debris Flow on the Basis of a Two-Dimensional Continuum Body Model” (Hiroshi Takebayashi, Masaharu Fujita), but I don’t understand if it is possible to determine a resistance coefficient based e.g. on physical characteristics of the soil, roughness of the running surface and more.

Thanks in advance for your kindly reply.

## コメント

Thank you for using Morpho2DH.

At present, we determine its value empirically. In most cases we use the default values 72. When changing the value, the value is varied in the range of 30 to 90. We need more research on the resistance coefficient.

The resistance coefficient, also known as the drag coefficient or the drag force coefficient, is a dimensionless quantity that relates the drag force experienced by an object moving through a fluid to the product of the fluid density, the object’s velocity, and a reference area.

The resistance coefficient is represented by the symbol Cd and is given by the equation:

Cd = (F_d / (0.5 * rho * V^2 * A))

where F_d is the drag force on the object, rho is the density of the fluid, V is the velocity of the object relative to the fluid, and A is the reference area of the object.

The resistance coefficient is a measure of the object’s ability to move through the fluid with minimal drag. A lower value of Cd indicates that the object is more streamlined and experiences less drag, while a higher value of Cd indicates that the object is less streamlined and experiences more drag.

The resistance coefficient is an important parameter in many engineering applications, such as aerodynamics, fluid dynamics, and naval architecture. It is used to design vehicles and structures that move through fluids with minimal drag, which can improve their efficiency and performance.

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