# Hydromechanics

## Objectives

Hydromechanics deals with the basic laws and mechanical concepts of "dry" water, i.e. without viscosity, and practical implications for the most important tasks of a coastal engineer.
In hydrostatics the understanding of the basic law under consideration of gravitational and other accelerations is taught. Afterwards the students will be enabled to use the implication of the basic law and its applications for the calculation of hydrostatic forces on areas of arbitrary form, and to establish floatability and flotation stability of solid bodies.
In hydrodynamics the conservation of mass, energy and moments for "dry" water is focussed on together with their combined applications to solve complex flow problems.

Later the definition of viscosity adapted from Newton's law of viscosity will be explained. The dramatic implications of the viscosity on the flow will be demonstrated so that students will be able to distinguish between the two concepts of "dry" and "wet" water. Furthermore, the students will understand the concept of the boundary layer of Prandtl as a kind of "golden bridge" between the old concept (ideal fluids) and the new concept (real fluids). The complexity of considering friction and the limits of theoretical descriptions will be explained using the example of laminar closed-conduit pipe flow, laminar groundwater flow, and turbulent pressure pipe and open channel flow.

The topics of the course Hydromechanics will be examined according to the new examination regulations in the exam of Hydromechanics (120 minutes). All further information can be found on Stud.IP.

## Topics:

• Tasks of hydromechanics and mechanical properties of water
• Hydrostatics
• Introduction to hydrodynamics
• Continuity equation
• Introduction to potential flow
• Energy theorem and momentum equation
• Combined application of the three conservation equations in hydromechanics
• Concept of critical water depth
• Surge and down surge
• BORDA losses and hydraulic jump
• Introduction to the real fluids
• NEWTON's law of viscosity
• Laminar and turbulent flow
• PRANDTL hypothesis: concept of the boundary layer
• Laminar pipe flow and laminar groundwater flow
• Turbulent open channel flow and turbulent pressure pipe flow

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