The Change of The Added Mass and Its Effects on Governing Equations

A wonderful phenomenon, not described before, should be referred to as the change of the added mass. The change of the added mass reveals its, for example, when a moving ship is stricken or pushed from the side. In that case, the added mass is increased several times ship’s mass and thus ship velocity is reduced substantially. There is no other explanation could explain this strange occurrence. Up to 60 years ago or so the added mass was ignored and the governing equations were built with this assumption for the fish locomotion and the surface vehicles. At least with this omission, the equations were consistent. Currently, this assumption has been challenged (transformation is not complete yet) and it has been replaced by the governing equations that partially include the added mass. The consistency was broken and now the governing equations is using the added mass but yet in the same time the properties such as the moment of inertia are calculated as if the added mass does not exist. In the previous papers in this series, the lens were placed on the rotation pivot points and defined the centroid of the added mass. In this discussion an attempt is made to remove the cloak created by the added mass coefficients. This effect shows that there is a change in the added mass and hence there should be an additional term in the fluid governing equation. The representation of the added mass coefficients while ignoring the issue of the total added mass is exclusive practice in the study of biology especially in the aquatic area and surface vehicles area.The usage of added mass coefficients cloaks the fact that while the added mass coefficients are constant, the total added mass varies during the maneuvering of the body. In fact, this change is so significant that it limits the ability of the aquatic body to produce propulsion. As it will be discussed here, the change in the added mass extracts or requires energy from the body. Thus, additional terms in governing equation are required to for the governing equations of fluid domain. In fact, this is one of the possible reasons for the instabilities reported in the literature in the calculations of fluid domain.The article hopefully will crate a small revolution in this area of fish locomotion and the surface vehicles