# Accession Number:

## AD0488868

# Title:

## THE EFFECT OF SURFACE TENSION ON SHIP WAVE RESISTANCE,

# Descriptive Note:

# Corporate Author:

## CALIFORNIA UNIV BERKELEY COLL OF ENGINEERING

# Personal Author(s):

# Report Date:

## 1966-07-01

# Pagination or Media Count:

## 114.0

# Abstract:

An extension of classical, Michell thin-ship theory to include the effect of surface tension is presented. An expression for the ships resistance is developed and is shown to consist of two parts. The gravity-wave resistance arises from the gravity-dominated wave train which trails the ship and the ripple resistance arises from the surface-tension-dominated ripple train which precedes the ship. The first section of this study is devoted to a comparison of the new theory with that of Michell. It is shown that the character of both the gravity-wave and ripple resistance expressions are similar to Michells Integral. One important difference exists in that both new resistance terms are identically zero for all ship speeds below a certain critical speed typically 0.8 fps. It is shown that in the limit of small surface tension, the gravity-wave resistance approaches Michells Integral and the ripple resistance approaches zero. Numerical computation shows that the difference between the total resistance and Michells Integral is insignificant for normal ship forms which are longer than five feet, but the difference is significant for ship models two feet long. The final section of this study is devoted to an examination of the effect of surface tension on the asymptotic behavior of the total resistance. It is shown that as the speed passes through the critical speed, the total resistance jumps from zero to some finite value. It is also shown that the troublesome terms which arise in the high-Froude number and shallow-draft limits of Michells Integral do not appear in the corresponding limits of the new theory. Author

# Descriptors:

# Subject Categories:

- Marine Engineering
- Fluid Mechanics