The Bagnold number is the ratio between the grain stress to the viscous fluid stress. The given below is the Bagnold number formula to calculate the Bagnold number. According to the Bagnold Number formula, It is the product of the particle density, the square of the grain diameter, linear concentration and shear rate, the resultant is divided by the dynamic viscosity of the fluid. If the value of the Bagnold number is large then the grain stress predominates in the flow.
The Bagnold number is still used by NASA to study the sand particle in mars. Use this Bagnold number formula for calculating the Bagnold number which is used for characterizing the sand flow.