10/6/2015 SMS 204: Integrative marine sciences1 SMS 204: Integrative marine sciences II Instructors: E. Boss and MJ Perry. Instructors: E. Boss and MJ.

04/19/2304/19/23SMS 204: Integrative marine SMS 204: Integrative marine

sciences sciences 11

SMS 204: Integrative SMS 204: Integrative marine sciencesmarine sciences II II

• Instructors: E. Boss and MJ Perry.Instructors: E. Boss and MJ Perry.

• Class web site:Class web site:http://misclab.umeoce.maine.edu/boss/classes/SMS_204/Syllabus.htmhttp://misclab.umeoce.maine.edu/boss/classes/SMS_204/Syllabus.htm

Emmanuel Boss

Finished 10-15min early.



Uncertainties: the human factor

How are regressions done?



• Some important concepts from last week:Some important concepts from last week:– Hydrostatic pressure- weight of water/areaHydrostatic pressure- weight of water/area– Continuity Continuity VV × × AA=constant=constant



• Archimedes's principle: Archimedes's principle: – The buoyancy force is equal to the weight of the liquid The buoyancy force is equal to the weight of the liquid

displaced by the object (where is this force coming displaced by the object (where is this force coming from?). from?).

For a floating object:

What is the balance of forces for a sinking object?



• Center of buoyancy vs. center of gravity: Center of buoyancy vs. center of gravity: Center of gravity:Center of gravity:

i i

iic m

mrr

Center of buoyancy: Center of gravity of displaced fluid.

When center of buoyancy is bellow the center of gravity the situation is unstable.

Separate centers of gravity and buoyancy allow organisms and plants to orient relative to the gravitational field:e.g. dinoflagellates, kelp.





Buoyancy issues for marine organisms:Buoyancy issues for marine organisms:

• Blubber is buoyant (0.7-0.9g cmBlubber is buoyant (0.7-0.9g cm-3-3))• Muscles (1.08g cmMuscles (1.08g cm-3-3) and bones (1.9g cm) and bones (1.9g cm-3-3) )

are denser than waterare denser than water• Air is buoyant (but compressible, that is Air is buoyant (but compressible, that is

buoyancy changes with pressure (depth))buoyancy changes with pressure (depth))

Some strategies:Some strategies:• Air in stomach (some sharks). Air in stomach (some sharks). • Swim bladder (many bony fishes, Swim bladder (many bony fishes,

physiologically regulated). physiologically regulated). • Large oily liver (Sharks). Large oily liver (Sharks).



Buoyancy and diving



Buoyancy engines on floats and gliders



• Energy:Energy:– Capacity to do work (force x distance).Capacity to do work (force x distance).

• Kinetic energy: Kinetic energy: mvmv22/2/2 [(m) (L [(m) (L22 T T-2-2)])]

• Pressure-volume energy: Pressure-volume energy: PVPV [(m L [(m L-1-1 T T-2-2)(L)(L33)])]

• Potential energy: Potential energy: mghmgh [(m) (L T [(m) (L T-2-2) (L)]) (L)]

• Other: internal energy, heat, light.Other: internal energy, heat, light.

Conservation of energy:Conservation of energy: mvmv22/2+mgh+PV=constant /2+mgh+PV=constant where we neglected where we neglected friction.friction.

Conservation of energy Conservation of energy per unit massper unit mass:: vv22/2+gh+P//2+gh+P/=constant =constant BernoulliBernoulli’’s principles principle



Important to remember:Important to remember:1.1.Holds only along a streamline (within a parcel Holds only along a streamline (within a parcel of water)of water)

2.2.Can convert kinetic energy here to pressure Can convert kinetic energy here to pressure somewhere else only if water there.somewhere else only if water there.

Different forms:Different forms:

vv22/2+gh+P//2+gh+P/=constant=constant

vv22/2+/2+gh+P=constantgh+P=constant

vv22/2g+h+P/g/2g+h+P/g=constant=constant

What is this?



Based on Bernoulli’s principle:How would pressure change along a fluid as it flows through a constriction?

Movie clip

Demo



Based on BernoulliBased on Bernoulli’’s principle: How can we measure s principle: How can we measure the velocity of a fluid using only pressure?the velocity of a fluid using only pressure?

Answer: the pitot tubeAnswer: the pitot tube

Direction of flow

Dynamic pressure

Flowing fluid



Squirting column:Squirting column:

Homework question

Hydro-electricity:Hydro-electricity:



u2/2g+z+P/g=constant



Application: flow above a disturbance Application: flow above a disturbance (Clams, ripples, houses, etc(Clams, ripples, houses, etc’’).).



Generate flow of small particles and solutes Generate flow of small particles and solutes into/out of sediments:into/out of sediments:



Today we discussed the following topics:Today we discussed the following topics:

Buoyancy.Buoyancy.

Energy conservation in fluids.Energy conservation in fluids.

Dynamic pressure.Dynamic pressure.

Questions?Questions?

10/6/2015 SMS 204: Integrative marine sciences1 SMS 204: Integrative marine sciences II Instructors: E. Boss and MJ Perry. Instructors: E. Boss and MJ.

Documents

marine organisms

gliders sms

center of buoyancy

buoyancy force

center of gravity

buoyancy engines

buoyancy issues

buoyancy changes