Froude number, Fr, is a dimensionless group which occurs frequently in the study of hydraulic phenomena involving a free surface.
where u is velocity, g acceleration due to gravity and L height. It represents the ratio of momentum force to gravitational force.
For physical modeling, for example, in naval architecture, Froude number is maintained constant by reducing the liquid velocity in the model in proportion to the square root of the linear dimension.
Often the term Froude number is used for the ratio u/(gL)1/2. This velocity ratio is also called Boussinesq Number.
Idadi ya Froude, Fr, ni kundi dimensionless ambayo hutokea mara kwa mara katika utafiti wa matukio ya hydraulic kuhusisha uso huru. ambapo u ni kasi, g kasi kutokana na mvuto na L urefu. Inawakilisha uwiano wa nguvu ya msukumo kwa nguvu ya mvuto. Kwa mfano, katika usanifu wa meli, idadi ya Froude huhifadhiwa mara kwa mara kwa kupunguza kasi ya kioevu katika mfano kwa uwiano wa mzizi wa mraba wa mwelekeo wa mstari. Mara nyingi neno Froude idadi ni kutumika kwa uwiano u/ (gL) 1⁄2. Uwiano huu wa kasi pia huitwa Nambari ya Boussinesq.