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Appendix L


Wall thickness for the concrete legs to float

Details of notations on page 51
Equation for floatation:

(L-1) [Edi78]30
Specific density equal 2.4 for concrete [Edi78]30, so inner-outer diameter ratio becomes:


Rewriting inner diameter in terms of outer diameter:


The thickness of a hollow cylinder is:


Minimum outer diameter to both allow buoyancy and to resist 100-year Atlantic wave:
Force from 100-year Atlantic wave = 40MN

Concrete grade = 55 MPa



Assuming post-tensioned to 20% of 55 MPa, so =0.2*55=11 MPa
(L-2)
(L-3)





Appendix M


Calculating velocity of sand particle in water

Details of notations on page 51
Stokes law for a sphere:

(M-1) [Tem53]31

For a sphere in water, the free body diagram will be such that the force pulling it down will equal to the drag force and buoyancy force together. In other words:

(M-2)

The buoyancy force will be the weight of displaced fluid, which depends on the volume taken up by the sphere. Volume of a sphere is:

(M-3)

So for buoyancy force, , where f is for fluid. (M-2) can therefore be re-written to:



This is re-arranged in the following steps, where p is short for particle:





(M-4)
For 0.5 mm diameter kiln sand with 2600 kg/m3 density for a silica crystal, its velocity in water where density is 998 kg/m3 and viscosity is 0.001 Pa*s is:


This means that Reynolds number is:

(M-5) [Sch79]32




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