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| what does the karman reduce to flat plate |
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| Stationary and Moving bodies under influences of F |
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| Branch of mechanics that deals with bodies at REST |
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| Branch of mechanics that deal with bodies in motion |
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| behavior of fluids in motion or at rest and their interaction with solids or other boundaries |
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| Same as FM, but sets fluids at rest to V=0 |
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| Study of motion of fluids that can be approx as INCOMPRESSOBLE |
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| Nusselt number = convection heat transfer/conduction heat transfer =hL/k |
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| a fluid always deforms under shear stress |
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| Stress and strain is proportional in solids, but in fluid, stress is proportional to strain rate |
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| Pressure P in relation to stress |
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| P is normal stress in fluid at rest |
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| GAS vs LIQUID wict filling space |
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| gas fills entire available space, liquid forms free surface |
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| Fluid sticks to solid surface - forms boundary layer due to viscocity |
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| Viscous vs Inviscid regions of flow |
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Definition
visc - flows in which friction effects are significant
invisc - viscos forces are nigligibly small compared to inertial or pressure forces |
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| Flow speed in form of Ma and incompressible approx |
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| Ma = V/c - approx inc if Ma < 0,3 this is because that usually approx less that 5% density change |
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| Steady - no change at a point w/time |
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| No change with location over specified region |
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| quantity of matter or region in space chosen to study |
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| The mass or region outside the system |
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| real or imaginary surface that separates the system from the surrounding (either fixed or movable |
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| fixed amount of mass, no mass accross boundary |
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| Properly selected region in space |
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| speed of sound for ideal gas |
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| viscoucity def/forklaring |
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| resistance to deformation |
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| Deformation is proportional to shear stress |
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| Viscocity in liquids vs gases IRT temp |
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| visc down when temp up for liquids, up when temp up for gasses. |
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"a curve that is everywhere tangent to the instantanious local velocity vector"
For steady, incomp 2d: u=(dY/dy) v=-(dY/dx) |
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| follow path of one particle over a time period |
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| Insert several particles and take instantanious pic |
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| Steady flow IRT stream, path and streakline |
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| all the same when flow is steady |
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| Rate of heat transfer for flat plate |
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| curves of constant scalar properties |
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| Inviscid region of flow (when to approx) |
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| for steady incomp flow - (du/dx)+(dv/dy)+(dw/dz)=0 |
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| When can you use stream and potential function? |
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| For incompressible, steady, irrotational 2-d |
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| What is friction force equal to on flat plate? |
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Definition
| Same as Tw*A (because Tw=(Ft/A)) |
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| h is equal to heat transfer coefficient |
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| Tau - what is this equal to (in terms of differential)? |
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| translation, rotation, linear strain shear strain |
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| Why do we use nondim navier stokes? |
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| to see relative effects of terms, and where one or more overpowers the other terms |
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| what is the Modified reynolds analogy |
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| It allows you to calculate heat transfer coeff from knowledge of friction. |
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| what is residual in CFD context |
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| it is a measure of how much our variables differ from the exact solutions. -put all terms on one side, the difference from zero is residual. |
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| starting point to get to a solutions. wrong in the beginning, but get more and more correct as we iterate. |
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| numerical method of marching towards solution |
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| solution converges to true value (not necessarilly) |
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| volume flow rate through pipe |
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Definition
V'=integral(0-2pi)integral(0-R)(u(r)*r)dr(d(theta)
=
2pi*integral(0-R)(u(r)*r)dr
flrste integralet blir 2pi, husk å gange med r på nste integral. |
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| Hva må du huske når du tar med tyngdekraft i navier stokes? |
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Definition
| Tyngdekraften fungerer som en dP/dy- altså navier stokes forkortes til dP/dy = rho*gy |
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| Reynolds analogy limitations |
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| limted to flows of fluid with prantl near unity such as gases and negiligable pressure gradient in flow direction |
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| Hva gjør du for å finne pressure field for u og v? |
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Definition
1 - sjekk for continuity
2 -kort ned navier stokes - finn deretter dP/dx fra x momentun og deretter dP/dy fra y momentum.
3 sjekk for smooth function!! dP/(dxdy) skal være lik dP(dydx) -
dersom dette ikke stemmer er det ikke smooth function, og vi kan ikke fortsette |
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| boundary conditions for oil film wall |
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| dv/dx = 0 ved x lik h! gå tilbake til dv/dx og sett inn x lik h - løs for C1 |
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| hvordan kan du bevise at en fartsprofil bare er funsksjon av en variabel tidlig? |
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Definition
| Sett inn i continuity equation - så står du igjen med kun f.eks. du/dx=0 - som sier at u bare er funksjon av x |
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| Can wald interval be trusted? when? |
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Definition
| Helst høy n - en dersom distibusjonen er normal eller approx normal kan vi stole på den d også |
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