# Bingham Number

Written by Jerry Ratzlaff on . Posted in Dimensionless Numbers

Bingham number, abbreviated as Bm, a dimensionless number, is the ratio of yield stress to visvous stress.

## Bingham Number formula

 $$\large{ Bm = \frac{ \tau_y \; l }{ \mu\; v } }$$

### Where:

 Units English Metric $$\large{ Bm }$$ = Bingham number $$\large{dimensionless}$$ $$\large{ l }$$ = characteristic length $$\large{ft}$$ $$\large{m}$$ $$\large{ \mu }$$  (Greek symbol mu) = dynamic viscosity of fluid $$\large{\frac{lbf-sec}{ft^2}}$$ $$\large{ Pa-s }$$ $$\large{ v }$$ = velocity $$\large{\frac{ft}{sec}}$$ $$\large{\frac{m}{s}}$$ $$\large{ \tau_y }$$  (Greek symbol tau) = yield stress $$\large{\frac{lbf}{in^2}}$$ $$\large{Pa}$$