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22 results for “flow”

Formulae (22)

Bernoulli's Principle

P + \tfrac{1}{2}\rho v^2 + \rho g h = \text{const}

Faster-moving fluid has lower pressure (energy conservation in flow).

Fluid MechanicsIntermediate

Continuity Equation

A_1 v_1 = A_2 v_2

Conservation of flow in an incompressible fluid.

Fluid MechanicsAdvanced

Bernoulli's Equation

P + \tfrac{1}{2}\rho v^2 + \rho g h = \text{const}

Energy conservation along a streamline.

Fluid MechanicsBasic

Volumetric Flow Rate

Q = Av

Volume of fluid passing per unit time.

Fluid MechanicsAdvanced

Reynolds Number

Re = \frac{\rho v L}{\mu}

Predicts laminar vs turbulent flow.

Fluid MechanicsAdvanced

Poiseuille's Law

Q = \frac{\pi r^4 \Delta P}{8\mu L}

Laminar flow rate through a pipe.

Fluid MechanicsAdvanced

Stokes' Drag

F = 6\pi\mu r v

Drag on a small sphere in viscous flow.

Fluid MechanicsAdvanced

Torricelli's Law

v = \sqrt{2gh}

Speed of fluid leaving a hole at depth h.

Electronics & CircuitsBasic

Current from Charge

I = \frac{Q}{t}

Current as the rate of charge flow.

EngineeringAdvanced

Bernoulli's Equation

P + \frac{1}{2}\rho v^2 + \rho g h = \text{const}

Conservation of energy in fluid flow.

EngineeringAdvanced

Reynolds Number

Re = \frac{\rho v L}{\mu}

Predicts laminar vs turbulent flow.

EngineeringBasic

Volumetric Flow Rate

Q = Av

Volume of fluid passing per unit time.

EngineeringIntermediate

Continuity Equation

A_1 v_1 = A_2 v_2

Conservation of mass in incompressible flow.

Materials & CivilIntermediate

Hydraulic Radius

R_h = \frac{A}{P}

Cross-sectional flow area divided by wetted perimeter.

Aviation & AeronauticsIntermediate

Specific Range

SR = \dfrac{GS}{\dot{f}}

Distance flown per unit of fuel; maximizing it gives best fuel economy.

Aviation & AeronauticsAdvanced

Reynolds Number

Re = \dfrac{\rho v L}{\mu}

Ratio of inertial to viscous forces; characterises airflow over an airfoil.

Aviation & AeronauticsBasic

Endurance

E = \frac{\text{fuel}}{\text{fuel flow}}

Time an aircraft can stay airborne.

Finance & InterestAdvanced

Net Present Value

NPV = \sum_{t=0}^{n}\frac{C_t}{(1+r)^t}

Present value of a stream of cash flows.

Finance & InterestAdvanced

Perpetuity

PV = \frac{C}{r}

Present value of an infinite constant cash flow.

Finance & InterestBasic

Payback Period

PP = \frac{\text{Initial Investment}}{\text{Annual Cash Flow}}

Time to recover an investment.

AccountingAdvanced

EBITDA

EBITDA = NI + Interest + Taxes + Depreciation + Amortization

Earnings before interest, taxes, depreciation and amortization — a proxy for core operating cash generation.

Geography & EarthAdvanced

Darcy's Law

Q = -KA\frac{\Delta h}{L}

Rate of groundwater flow through porous rock.