Besides temperature, particle size, and fluid viscosity, what other factors affect Brownian motion in a suspension?
Let's say I have a suspension and wish to increase the Brownian movement of its particles, is there a way I can do so without having to increase its temperature? What other things can I do to the suspension to achieve this (e.g. could I change the surface charges of the particles? Could I sonicate the suspension? Could I run an electric current through the suspension? Could I run a magnetic field around the suspension?)
Thank you.
Dear Kevin,
Besides temperature, particle size (volume), and fluid viscosity, other factors that may affect the Brownian motion in a suspension are:
- particle shape (whether it is spherical or not, ellipsoidal -prolate ellipsoids, oblate ellipsoids or scalene ellipsoids-, etc.) and magnetic anisotropy, which refers to the crystallographic anisotropy of the particles and their divergence from the ideal sphere topology
- application of external magnetic fields
- the magnetic properties of the particles
- whether the particles are monodisperse or not
- whether the particles are single magnetic domains or not
Hope this is useful,
Jose
P.D.: You can find extended information in Section 3.4 of the attached pdf
Brownian motion is a random motion of nanoparticles within the base fluid and results from continuous collisions between the nanoparticles and the molecules of the base fluid. Therefore, turbulence of flow and circulating eddies can contribute in promoting this random motion.
I think that the use of the magnetic field may retards the random motion of nanoparticles and thus suppresses the Brownian motion.
any factor that affects the partcle's movement in a fluid impacts the rate of Brownian motion, such as: increased temperature, increased number of particles, small particles size, low viscosity and turbulent flow
Dear Kevin Hii
The concentration of the particles in the fluid is one of the important factors, which will significantly affect the Brownian motion. Using suitable and optimized mechanical techniques (Ultrasonication, high pressure homogenization, etc.) or chemical techniques (stabilizers, pH adjustment) may result in deceasing the aggregation phenomenon and increase the Brownian motion of particles.
Dear Muneer,
yes, since Kevin asked about factors that affect Brownian motion, both the factors that foster Brownian motion and those that prevent it have an impact.
in this case, applying a magnetic field causes the magnetic spins of the particles to align with the magnetic field lines, which may involve physical rotation of the particles. Moreover, after removing the magnetic field, some remanent magnetization remains, which still affects further motion of the particles.
Regards
Jose
Brownian motion mechanism is interested when studying fluid mechanics under different effects.
Apparently, you mean only external influences upon Brownian motion. The acceleration of the Brownian motion of particles in suspension is also influenced by factors such as shape (for example, if the particles have a long shape, then the translational Brownian motion is also superimposed by a rotational movement that increases the probability of collision of such particles; etc.); heterogeneity (in the sense of heterogeneity of the material); proportion of different particle sizes (depending on the characteristics of the suspension, different optimal proportions of particles occur; by the way, finding the optimal proportion of heterogeneous particle sizes under fixed other characteristics and conditions is a very interesting mathematical problem).
The above-listed factors, obviously, are not external factors of influence, – they are "internal" factors.
Further, from the external factors listed by you, the last two factors influencing the acceleration of Brownian motion.
I am looking for a clarification on how the surface tension could affect the Brownian motion. Wouldn't the surface tension be a valid factor of the Brownian motion? Wouldn't the surface tension override the Brownian motion in some cases?
Brownian motion occurs to the effect of fluid particles or atoms, ie liquids and gases, in a rapid, random movement on small particles suspended in the liquid. Brownian motion, which tends to disperse particles as widely as possible is the main force that causes diffusion. Because of the random movement of atoms of molecules into the inhibitors, an even distribution of larger particles occurs within the medium.
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