![]() This number is almost 40 times larger than the viscosity of air. This gives us a Reynolds number of (which hey, also matches the range you posted - good start!): And let's assume a light breeze, say 5 m/s. Let's then take a normal day at standard temperature and pressure (STP) so that the kinematic viscosity of air is $\nu = 15.11e-6$. Adults rarely exceed 16mm in length, so let's just approximate and say they are 10mm long, so as a sphere they would have a radius of 5mm. Let's assume that a mosquito is approximately a sphere. So, when this number is small, the viscous forces dominate and when it is large, the inertial forces dominate. This can also be thought of as the ratio of the inertial forces to the viscous forces. Where $u$ is the fluid velocity, $L$ is a representative length scale and $\nu$ is the kinematic viscosity of the fluid. What you need to compare when looking at bodies of different sizes and asking how the forces relate, is in general, the Reynolds Number as you included in your question. In other words, is it possible to scale up the insect flying "experience" to the human level, and get an idea of what the human equivalent of the viscosity involved is? I appreciate it may be impossible to answer this question without referring back to the flight dynamics of insects, in which case my apologies as there may be no current answer. Instead I wonder do we know, compared to the human experience with respect to the fluid viscosity difference between still air and water, what air "feels" like to move through for an insect, such as a mosquito? For this reason, this intermediate range is not well understood. The range of Reynolds number in insect flight is about 10 to $10^4$, which lies in between the two limits that are convenient for theories: inviscid steady flows around an airfoil and Stokes flow experienced by a swimming bacterium. This article implies that insect flight is still a subject of active investigation. ![]() I don't wish to ask a biology based question, or how any insect actually flies, which can be found at Insect Flight. On that sort of scale, I wonder is it possible to estimate how normal still air applies in terms of viscosity, to a mosquito or other similar sized insect, utilising standard fluid dynamics techniques? If I go for a swim though, I will immediately notice the viscosity of the water and the effort needed to move through it. Oxygen dynamic and kinematic viscosity at atmospheric pressure and varying temperature:ĭynamic viscosity of oxygen at varying temperature and 1, 10, 50 and 100 bara (14.If I go for a walk at, say 4 km/hour, unless there is a breeze blowing, I probably won't notice the air around me at all. See also other properties of Oxygen at varying temperature and pressure: Density and specific weight and Specific heat (heat capacity), and Thermophysical properties at standard conditions,Īs well as dynamic and kinematic viscosity of air, ammonia, benzene, butane, carbon dioxide, ethane, ethanol, ethylene, methane, methanol, nitrogen, propane and water. ![]() Temperature Choose the actual unit of temperature: While the kinematic viscosity is given as cSt, m 2/s, and ft 2/s The output dynamic viscosity is given as Pa*s, N*s/m 2, cP, mPa*s, lb f*s/ft 2 and lb m/(ft*h), The calculator below can be used to estimate oxygen dynamic or kinematic viscosity at given temperatures and atmospheric pressure. Oxygen phase diagram Online Oxygen Viscosity Calculator Tabulated values and viscosity units conversion are given below the figures. Absolute or dynamic viscosity is used to calculate Reynold's Number to determine if a fluid flow is laminar, transient or turbulent. The viscosity of a fluid is a measure of its resistance to gradual deformation by shear stress or tensile stress.įor further definitions, go to Absolute (dynamic) and kinematic viscosity. ![]()
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