With shear thickening fluids, what happens on a molecular level to make them act the way they do?
540888
My understanding is that the shear stretches the molecules out, allowing more interactive sites to be exposed.  In a linear form, the molecule becomes more able to participate in bonding with its neighbor.
953035
a) pseudo solid. An example would be when you mix a lot of corn starch to water, creating a matrix. When you stir it quickly, it cracks and breaks, but when you stir it slowly, it behaves as a liquid. So this pseudo solid has some solid properties, but really is a colloid liquid.\nb) Annealing. (metallurgy), a heat treatment that alters the microstructure of a material causing changes in properties such as strength and hardness. This process is done for steel and other alloys in machining high quality parts for aeronautics, tooling, etc.
956979
it has to do with the viscosity of a fluid at different temperatures. like oil. oil comes in different thicknesses. 10w-20 10w-30 and so on. the thickess is a 90 weight gear oil and if it 20 degrees outside it wont flow just as water wont when it freezes.the thicker a fluid is and as the temperature gets colder it wont flow.
947088
Pressure a higher pressure will push the molecules closer to each other so the reaction takes place faster cause the molecules colide more often.\n\nAmounts of the chemicals, will take longer as you increase each to fully react because there is more to react.\n\nConcentrations of the liquids a higher concentration will have more of the molecules to react.\n\nAnd the amount of activation energy if the amount is low the reaction will procede at a faster rate.
27784
By vibrating the molecules.
351963
You are talking about viscosity of a liquid. In short: as temp goes up, viscosity or resistance goes down (however, this is not true for all liquids).\n\nViscosity is a measure of the resistance of a fluid to deformation under shear stress It is commonly perceived as "thickness", or resistance to pouring. Viscosity describes a fluid resistance to flow and may be thought of as a measure of fluid friction. Thus, methanol is "thin", having a low viscosity, while vegetable oil is "thick" having a high viscosity.\n\nBasically in a liquid you have a bunch of molecules smashing into each other at a certain "speed". The higher the temperature the faster they move around and the more "spread out" they become. Therefore as temperature goes up it becomes easier for things to move through the liquid and vise versa. Of course, this is true for most liquids but not all. See below for a great site that explains more.
478094
Yup and mine are danceing on my head\n\nofcourse not\n\nHair consists 90% of a biological polymer, α-keratin, and about 10% water, which modifies its mechanical properties. This α-helically coiled protein is further wound into supermolecular coiled-coil microfibrils, many of which are held together with a protein glue to form long macrofibrils, which are packed inside dead hair cells about 100 µm long by 3 µm across. Several of these associate to form one strand of hair, which is covered with tiny surface scales. The ends of individual keratin chains are high in the amino acids proline (an α-helix breaker) and cysteine. Adjacent keratin chains are held together by many disulfide bonds bridging their cysteines. These links are very robust; virtually intact hair has been recovered from ancient Egyptian tombs. Different parts of the hair have different cysteine levels, leading to harder or softer material.
1031001
You could class them as soft solids, since they do not flow. They may be very viscous liquids... but solid is the closest definition.\n\nThe are not truley fluid {which means "gas or liquid" in Physics}, since I can put it in a bowl and it won't coat the bottom.
127488
Their difference in polarity and density are probably the two most likely properties to affect the rate of separation. Molecular weight differences between the two liquids would probably have some impact, also temperature would effect the rate of separation.
999288
well, others might have told you it is pressure, and actually even i would have gone for it!\nbut since you have mentioned in particular on a fluid, then this ratio can also be called as Bulk's modulus(though this applies even to solids)\nit can also be the coeff of viscosity taken velocity gradient times\nthere can be various other depictions also
18016
Since solids do not flow, then no for most.  Although, not all solids are the same.  Looking at amorpheous solids such as glass and newer metals that were supercooled as a liquid.  Glass has an extremely high viscocity because it is a liquid that is flowing really slowly.  If you look at the case of the cathedrals built in the old times, glass is thicker as it is closer to the ground.
344434
To correctly simulate the rheology of concentrated suspensions at high shear rates requires the inclusion of hydrodynamic forces between particles. The computation of such interactions is very intensive, and it presents a significant challenge: to produce algorithms that enable a study of systems with large numbers of particles. The work of Brady and coworkers in the early eighties [1] showed the way forward to such a goal. The technique, Stokesian Dynamics presents a formalism for studying such systems. We first write down the Langevin equation for a colloidal particle within a hydrodynamic medium:\n\nFH + FC + FB = M · dU/dt\n\nHere, F represents forces acting on an individual particle: Hydrodynamic, Colloidal (charge repulsion/attraction for example) and Brownian forces. M is the mass of the particle, and U its velocity.Within a colloidal system, the time scales of interest dictate that inertia may be neglected. Thus the right hand side of above equation can be neglected. We also work with the assumption that the fluid obeys the Stokes equations, i.e. we are within a low Reynolds number regime. Thus the hydrodynamic forces can be considered linear in the velocities, therefore FH = R·U, where R is a resistance tensor, the elements of which describe the hydrodynamic interactions between individual particles. To simulate colloid particles, we need to determine the particles velocities at each time step, thus the above equation becomes:\n\nU = -R-1 · (FC + FB)\n\nThus solving for U requires the inversion of the resistance matrix R. This typically restricts the size of the systems that one can study to less than 100 particles. In order to simulate systems on a larger scale, Ball and Melrose [2] have proposed an approximation that is applicable to colloids at high concentrations in shear flow. They argue that at such concentrations, where the typical interparticle spacing is small, the near-field terms in the resistance matrix (which are given by lubrication theory) will dominate in shear flow. Thus R can be made sparse; this greatly increases computational efficiency. The method is now typically of O(N2) compared to O(N3) for the full matrix, making the study of larger systems feasible (typically as much as 4,000 particles). Even though the resistance tensor is sparse and consists of near-field terms, the inversion of such a matrix results in a many-bodied far-field mobility tensor. Ref. [2] gives full details on the technique, in particular how to correctly handle the correlated Brownian forces through use of a 2nd order difference scheme. The code has been implemented and validated. It has a suite of colloid interactions, including charge, depletion, and polymer coats. Particles may interact with just squeeze lubrication or with full modes of shear and rotation. Nearest neighbours are identified through the construction of a Delaunay mesh which is co-moving with the particle centres. Sample results from using this algorthim are given in the Colloid Rheology section of this site.\n\nReferences\n\nBrady, J. F. and G. Bossis, "The rheology of concentrated suspensions of spheres in simple shear flow by numerical simulation," J. Fluid Mech, 155, 105-129 (1985) \nBall, R. C. and J. R. Melrose, "A simulation technique for many spheres in quasi-static motion under frame-invariant pair drag and Brownian forces," Physica A, 247, 444-472 (1997)
459779
if something is viscoelastic, it is both viscous - it will deform irreversably, and elastic - it will deform reversibly. everything is really viscoelastic, but some things, like rubber bands are mostly elastic, and some, like liquids, are mainly viscous.\n\nviscoelastic materials will mostly revert to form when they undergo small stresses, but will deform irreversibly under large stress. good examples are metal springs - they will revert completely if you only pull a little bit, but if you really stretch out a spring, it will lose its springyness.
154119
Water is a Newtonian fluid, meaning its shear stress is linearly proportional to rate of shearing strain. Agitation will not affect its viscosity. Pressures will not affect it either unless they are extremely high.\n\nThe viscosity of water generally decreases as temperature increases. Water at 32ºF has an absolute viscosity of 1.794 cp (centipoise). At 200ºF, its viscosity will have decreased to .305 cp.\n\nThis means that water will flow slightly more easily at higher temperatures.\n\nFor some mathematical models, check out this link:\n\nhttp://en.wikipedia.org/wiki/Temperature_dependence_of_liquid_viscosity
316023
intermolecular polarity and the fact that fluids dont compress the way gases do?
1054682
It "fizzes".  When you put acid on CaCO3 it reacts to release CO2 gas:\n\nCaCO3 + 2H+(aq)  -> Ca2+(aq) + H2O + CO2(g)
582644
The gelatine protein molecules cross-link to each other forming a "gel", a soft solid. The gelatine gel is both shear-reversible and temperature reversible (see ref.). This means it can turn back to a liquid at slightly below body temperature or by being energetically stirred, but can be reconstituted as a gel by cooling again.