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fluid mechanics //مجموعة مشاركات(( لعلم الموائع)) !!يمكنك الاضافة والمشاركة

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  1. [11]
    حسن هادي
    حسن هادي غير متواجد حالياً
    عضو متميز
    الصورة الرمزية حسن هادي


    تاريخ التسجيل: Nov 2006
    المشاركات: 1,338
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    Fluid Mechanics and Propulsion Group

    Links to Laboratories

    Other Links

    Faculty

    ProfessorGeneral Research Interests
    Sanford Fleeter, Ph.D.
    Sangtae Kim, Ph.D.
    Patrick B. Lawless, Ph.D.
    Michael W. Plesniak, Ph.D.
    Carl Wassgren, Ph.D.
    Steve Wereley, Ph.D.
    Emeritus Faculty

    • Robert W. Fox
    • Victor W. Goldschmidt
    • Joe D. Hoffman
    • Mel R. L'Ecuyer
    • Alan T. McDonald
    • H. Doyle Thompson
    Textbooks by Faculty Members


    مع المودة لكل المهندسين

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  2. [12]
    حسن هادي
    حسن هادي غير متواجد حالياً
    عضو متميز
    الصورة الرمزية حسن هادي


    تاريخ التسجيل: Nov 2006
    المشاركات: 1,338
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    الروابط فعالة

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  3. [13]
    حسن هادي
    حسن هادي غير متواجد حالياً
    عضو متميز
    الصورة الرمزية حسن هادي


    تاريخ التسجيل: Nov 2006
    المشاركات: 1,338
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  4. [14]
    حسن هادي
    حسن هادي غير متواجد حالياً
    عضو متميز
    الصورة الرمزية حسن هادي


    تاريخ التسجيل: Nov 2006
    المشاركات: 1,338
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  5. [15]
    حسن هادي
    حسن هادي غير متواجد حالياً
    عضو متميز
    الصورة الرمزية حسن هادي


    تاريخ التسجيل: Nov 2006
    المشاركات: 1,338
    Thumbs Up
    Received: 7
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  6. [16]
    حسن هادي
    حسن هادي غير متواجد حالياً
    عضو متميز
    الصورة الرمزية حسن هادي


    تاريخ التسجيل: Nov 2006
    المشاركات: 1,338
    Thumbs Up
    Received: 7
    Given: 0

  7. [17]
    حسن هادي
    حسن هادي غير متواجد حالياً
    عضو متميز
    الصورة الرمزية حسن هادي


    تاريخ التسجيل: Nov 2006
    المشاركات: 1,338
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    FLUID MECHANICS LABORATORY
    Hesse Hall 140



    Classical fluid mechanics, Biofluid mechanics,
    Rotating flows, Experimental Techniques,
    Vortex dynamics, Airfoil wake vortices,
    Bluff body aerodynamics, Turbulent flows,
    � etc.
    Experimental fluid mechanics, Bio-MEMS,
    Micro-fluidic systems, Biofluid mechanics,
    Free surface flows, Hydroacoustics,
    � etc.





    Maintained by: the industrious students of the FML. Last updated June 28, 2000.

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  8. [18]
    حسن هادي
    حسن هادي غير متواجد حالياً
    عضو متميز
    الصورة الرمزية حسن هادي


    تاريخ التسجيل: Nov 2006
    المشاركات: 1,338
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    MATTER and MATERIALS

    حسن هادي
    "The Fundamentals of Fluids"


    viscosity


    buoyancy


    density


    volume


    mass


    particle theory


    Fluids under pressure can exert forces that can be used by us to do work. Fluids form the basis for pneumatic and hydraulic systems which are used in industries such as automobile manufacturing ( brakes ), hoists found in service stations, dentist's chair, aeronautics, submarines, the shipping industry and the list can go on and on. Some fluids can be compressed (gases) while others (liquids) cannot.


    FLUIDS CAN BE LIQUIDS OR GASES.

    FLUIDS, INCLUDING AIR AND WATER,

    ARE VERY IMPORTANT AND ARE ESSENTIAL TO MANY INDUSTRIES.


    The viscosity of fluids varies. For example: oil, water, syrup, liquid detergent and ketchup have different viscosities. Temperature does affect a fluid's flow rate and this can be very important to know. Just imagine all the companies that manufacture chocolate. Think of all the chefs preparing their sauces. Think of the hot car engine affecting the car's oil or for that matter, think of how the car first starts and runs on that cold winter morning. Look how difficult it is to pour syrup if it has been refridgerated.


    Usually, the greater the viscosity, the greater the density. Density is defined as the mass per unit volume of a substance. In other words, density is mass divided by volume. Massis the amount of matter in an object and is measured in grams or kilograms, and volume is the amount of space occupied by an object. Volume is measured in cubic units such as cm .

    The viscosity and density of fluids affects objects placed in those liquids. A buoyant force is the upward force on objects submerged in fluids. In somes cases this could cause the object to float when normally gravity would cause it to sink. (Try floating an egg or a golf ball)


    3

    During the next 18 - 20 science classes, you will be engaged in many activities and labs. involving fluids and fluid mechanics. The unit outline can be found on the next page.


    Try these out!


    FLOAT OR SINK - you find out


    FLOATING LOG - give this a go


    BUOYANCY - in liquids


    Information to help!


    Mass, Volume and Density


    Pressure


    Fluid Mechanics

    - hydraulics and pneumatics


    bj




    Fluid mechanics
    at work.


    NEXT


    ( mouse over )




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    A great activity to show how submarines dive and surface.


    تحياتي اخوكم حسن

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  9. [19]
    حسن هادي
    حسن هادي غير متواجد حالياً
    عضو متميز
    الصورة الرمزية حسن هادي


    تاريخ التسجيل: Nov 2006
    المشاركات: 1,338
    Thumbs Up
    Received: 7
    Given: 0

  10. [20]
    حسن هادي
    حسن هادي غير متواجد حالياً
    عضو متميز
    الصورة الرمزية حسن هادي


    تاريخ التسجيل: Nov 2006
    المشاركات: 1,338
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    Turbulence, and Fluid Mechanics in General

    20 May 2007 10:46


    The story is told of many giants of modern physics, but most plausibly of Heisenberg, that, on his death-bed, he remarked that the two great unsolved problems were reconciling quantum mechanics and general relativity, and turbulence. "Now, I'm optimistic about gravity..."
    Fluid flow, it should be said, is in one sense very well understood; since the early 1800s there's been a fine, non-linear, Newtonian equation for the velocity field that seems to work, the Navier-Stokes equation. (Like Newton's law of gravitation, it should be branded on to anyone who babbles that non-linear physics is "new" or "non-Newtonian".) One of its properties is that it's invariant so long as the Reynolds number --- density*(length scale)*(velocity scale)/viscosity --- stays the same. This is why wind-tunnels work: the model in the tunnel is shorter than the original, but the mean speed is higher, so the flows are equivalent. When the Reynolds number is small, the equation is mathematically nice, the non-linearities are small, and we can solve the equation. The stream-lines --- the paths followed by small tracer particles dropped into the fluid --- form nice layers around the boundaries of the flow, which is why the flow is called laminar, and these laminæ are stable.
    As you turn up the Reynolds number, the non-linearities become important, and the flow gets uglier --- it is no longer steady, but erratic (probably chaotic in the strict sense), and the nice regular stream-lines and their laminæ get snarled and then completely confused; eddies and vortices form and spin and dissolve without much obvious pattern, and the develop their own eddies in turn; odd structures with names like "von Kármán streets" appear. (Pictures make this a lot clearer; van Dyke's Album of Fluid Motion is full of handsome ones, but short on explanation.) Turbulence --- yea, "fully developed turbulence", even --- is when this decay into confusion is complete, when there are eddies and motions on all length scales, from the largest possible in the fluid on down to the so-called "dissipation scale," which is (roughly!) the minimum eddy size, as set by the mechanical properties of the fluid (its viscosity and the like). When faced with this confusion, if not well before, we give up and turn to statistics; we begin to ask questions about the statistical properties of the flow --- if you will, about all possible flows we could see under given conditions. Here we can make some nice observations, and even come up with two well-confirmed empirical laws about these statistics, and endless graphs.
    So what, you may ask, is the fabled "problem of turbulence"? In essence, this: what on Earth do our statistics and our equation have to do with each other? A solution to the problem of turbulence would be, more or less, a valid derivation from the Navier-Stokes equation (and statements about the appropriate conditions) of our measured statistics. Physicists are very far from this at present. Our current closest approach stems from the work of Kolmogorov, who, by means of some statistical hypotheses about small-scale motion, was able to account for the empirical laws I mentioned. Unfortunately, no one has managed to coax the hypotheses from the Navier-Stokes equation (sound familiar?) and the hypotheses hold exactly only in the limit of infinite Reynolds number, i.e. they are not true of any actual fluid. So what's to do? Well, all sorts of things, including more or less direct simulations of flows by cousins of cellular automata called "lattice gasses" (which is how I connect to the subject, though very vaguely). One approach uses the vorticity (the curl of the velocity field, which tells us about how the fluid swirls), since it turns out to be possible to identify some (more or less) simple objects in the flow, called vortex lines or vortex tubes, work out how they interact (there's a Hamiltonian), and then use statistical mechanics to calculate various emergent properties --- which, if you use just the right approximations, and tolerate negative temperatures (which are not impossible, and actually hotter than infinity) gives you the Kolmogorov laws. This could've been custom-tailored for my philosophical and methodological biases, which makes me suspicious, as do all the leaps in the approximation scheme used. (For the pro-vorticity case, see Chorin; reasons for caution

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