Fluid is a subtance (liquid or gas) which can deform continously under the action of shear stress.
There are 2 types of fluid:
Ideal Fluid: which does not have surface tension, viscosity and are incompressible.
Real Fluid: Fluids that are not Ideal.
In reality Ideal Fluid does not exist.
Density,\rho =\frac{mass}{Volume}
G=\frac{\rho }{{\rho}_{Standard}}
\gamma =\rho g
K=-\frac{dP}{{dV}/{V}\;}=\frac{dP}{{d\rho }/{\rho }}
\tau =\mu \frac{du}{dy}
\upsilon =\frac{\mu }{\rho }
{{\mu }_{liq}}=a{{10}^{\left( \frac{b}{T-c} \right)}}
{{\mu }_{gas}}=\frac{a\sqrt{T}}{1+{}^{b}/{}_{T}}
\Delta {{P}_{1}}=\frac{2\sigma }{r}
\Delta {{P}_{2}}=\frac{4\sigma }{r}
\Delta {{P}_{3}}=\frac{2\sigma }{d}
h=\frac{4\sigma \cos \theta }{\gamma d}
G= Spective Gravity or Relative Density of Fluid
{{\rho}_{Standard}}= Density of some standard fluid at standard temperature (usually water at 4{}^\circ C)
\gamma = Specific Weight or weight density of liquid
g= Acceleration due to gravity
K= Bulk Modulus
dP= Increase in Pressure
{{dV}/{V}}= Chnage in Volume per unit Volume
\tau = Shear Stress
\mu = Dynamic Viscosity
\frac{du}{dy}= Velocity Gradient
\upsilon = Kinematic Viscosity
{{\mu }_{liq}}= Dynamic viscosity of liquid
{{\mu }_{gas}}= Dynamic viscosity of gas
\sigma= Surface Tension
NEWTONIAN AND NON NEWTONIAN FLUIDS
General relationship between shear stress and velocity gradient is,
\tau =A{{\left( \frac{du}{dy} \right)}^{n}}+B
| Types of Fluids | Examples |
| Dilatant | Suspended Starch or sand, sugar in water, butter |
| Newtonian | Water, air, alcohol |
| Pseudo Plastic | Paints, polymer solutions, blood, paper pulp, syrup, milk |
| Rheopectic | Gypsum, lubricants |
| Bingham Plastic | Tooth Paste, Sewage sludge, drilling mud |
| Thixotropic | Printer's Ink, Ketchup, enamels |
