Formulas for ViscosityA widely used formula for the calculation of viscosity of gases is the Sutherland Equation given bywhere b and S are constants and T is temperature expressed in Eq. 1.8 .For air and . Power Law is another approximation to calculate viscosity and isgiven by
where is the value of viscosity at a reference temperature ,which could be 273K. An empirical fit for the viscosity of liquids is For water, = 273.16K, = 0.001792 kg/(m.s), a=-1.94,b = -4.80 and c = 6.74. Another empirical formula for liquids is the Andradeequation namely,
where and are constants and is the temperature in K (c) Aerospace, Mechanical & Mechatronic Engg. 2005University of Sydney |
The value of the dynamic viscosity coefficient is found to be a constant with pressure but the value depends on the temperature of the gas. Sutherland provides an equation for the dependence on temperature T: mu = mu0. ((T / T0)^1.5). ((T0 + 198.72) / (T + 198.72)).
Viscosity Of Air At 20 C
- Temperature Dependence of ViscosityWatch More Videos at: By: Er. Himanshu Vasishta, Tutorials.
- Viscosity of a fluid is strongly dependent on temperature and is a weak function of pressure. For example, when the pressure of air is increased from 1 atm to 50 atm, its viscosity increases only by about 10 percent allowing one to ignore its dependence on pressure.
Viscosity Of Air At Standard Conditions
| Temperature | Density | Specific Heat | Thermal Conductivity | Dynamic Viscosity | Expansion Coefficient |
|---|---|---|---|---|---|
| K | kg/m3 | J/(kg.K) | W/(m.K) | kg/(m.s) | K-1 |
| 200 | 1.766 | 1003 | 0.0181 | 1.340E-5 | 3.998E-3 |
| 250 | 1.413 | 1003 | 0.0223 | 1.610E-5 | 4.996E-3 |
| 280 | 1.271 | 1004 | 0.0246 | 1.750E-5 | 3.724E-3 |
| 290 | 1.224 | 1005 | 0.0253 | 1.800E-5 | 3.840E-3 |
| 298 | 1.186 | 1005 | 0.0259 | 1.840E-5 | 4.005E-3 |
| 300 | 1.177 | 1005 | 0.0261 | 1.850E-5 | 3.823E-3 |
| 305 | 1.16 | 1005.5 | 0.02645 | 1.875E-5 | 2.931E-3 |
| 310 | 1.143 | 1006 | 0.0268 | 1.900E-5 | 2.975E-3 |
| 315 | 1.1265 | 1006 | 0.02715 | 1.920E-5 | 2.929E-3 |
| 320 | 1.11 | 1006 | 0.0275 | 1.940E-5 | 2.973E-3 |
| 325 | 1.093 | 1006.5 | 0.0279 | 1.965E-5 | 3.111E-3 |
| 330 | 1.076 | 1007 | 0.0283 | 1.990E-5 | 3.160E-3 |
| 335 | 1.0595 | 1007 | 0.02865 | 2.010E-5 | 3.115E-3 |
| 340 | 1.043 | 1007 | 0.029 | 2.030E-5 | 3.164E-3 |
| 345 | 1.026 | 1007.5 | 0.02935 | 2.055E-5 | 3.314E-3 |
| 350 | 1.009 | 1008 | 0.0297 | 2.080E-5 | 3.370E-3 |
| 355 | 0.9964 | 1008.5 | 0.03004 | 2.101E-5 | 2.529E-3 |
| 360 | 0.9838 | 1009 | 0.03038 | 2.122E-5 | 2.561E-3 |
| 365 | 0.9712 | 1009.5 | 0.03072 | 2.143E-5 | 2.595E-3 |
| 370 | 0.9586 | 1010 | 0.03106 | 2.164E-5 | 2.629E-3 |
| 375 | 0.946 | 1010.5 | 0.0314 | 2.185E-5 | 2.664E-3 |
| 380 | 0.9334 | 1011 | 0.03174 | 2.206E-5 | 2.700E-3 |
| 385 | 0.9208 | 1011.5 | 0.03208 | 2.227E-5 | 2.737E-3 |
| 390 | 0.9082 | 1012 | 0.03242 | 2.248E-5 | 2.775E-3 |
| 395 | 0.8956 | 1012.5 | 0.03276 | 2.269E-5 | 2.814E-3 |
| 400 | 0.883 | 1013 | 0.0331 | 2.290E-5 | 2.854E-3 |
| 450 | 0.785 | 1020 | 0.0363 | 2.490E-5 | 2.497E-3 |
| 500 | 0.706 | 1029 | 0.0395 | 2.680E-5 | 2.238E-3 |
| 550 | 0.642 | 1039 | 0.0426 | 2.860E-5 | 1.994E-3 |
| 600 | 0.589 | 1051 | 0.0456 | 3.030E-5 | 1.800E-3 |
| 700 | 0.504 | 1075 | 0.0513 | 3.350E-5 | 1.687E-3 |
| 800 | 0.441 | 1099 | 0.0569 | 3.640E-5 | 1.429E-3 |
| 900 | 0.392 | 1120 | 0.0625 | 3.920E-5 | 1.250E-3 |
| 1000 | 0.353 | 1141 | 0.0672 | 4.180E-5 | 1.105E-3 |
| 1200 | 0.294 | 1175 | 0.0759 | 4.650E-5 | 1.003E-3 |
| 1400 | 0.252 | 1201 | 0.0835 | 5.090E-5 | 8.333E-4 |
| 1600 | 0.221 | 1240 | 0.0904 | 5.490E-5 | 7.014E-4 |
| 1800 | 0.196 | 1276 | 0.097 | 5.870E-5 | 6.378E-4 |
| 2000 | 0.177 | 1327 | 0.1032 | 6.230E-5 | 5.367E-4 |