Electroacoustic phenomena arise when ultrasound propagates through a fluid containing ions. The associated particle motion generates electric signals because ions have electric charge. This coupling between ultrasound and electric field is called electroacoustic phenomena. The fluid might be a simple Newtonian liquid, or complex heterogeneous dispersion, emulsion or even a porous body. There are several different electroacoustic effects depending on the nature of the fluid.
Ion vibration current (IVI) and potential, an electric signal that arises when an acoustic wave propagates through a homogeneous fluid.
Streaming vibration current (SVI) and potential, an electric signal that arises when an acoustic wave propagates through a porous body in which the pores are filled with fluid.
Colloid vibration current (CVI) and potential, an electric signal that arises when ultrasound propagates through a heterogeneous fluid, such as a dispersion or emulsion.
Electric sonic amplitude (ESA), the inverse of the CVI effect, in which an acoustic field arises when an electric field propagates through a heterogeneous fluid.
Ion vibration current
Historically, the IVI was the first known electroacoustic effect. It was predicted by Debye in 1933.
Streaming vibration current
The streaming vibration current was experimentally observed in 1948 by Williams. A theoretical model was developed some 30 years later by Dukhin and others. This effect opens another possibility for characterizing the electric properties of the surfaces in porous bodies. A similar effect can be observed at a non-porous surface, when sound is bounced off at an oblique angle. The incident and reflected waves superimpose to cause oscillatory fluid motion in the plane of the interface, thereby generating an AC streaming current at the frequency of the sound waves.
The electrical double layer can be regarded as behaving like a parallel plate capacitor with a compressible dielectric filling.
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In this course we study heat transfer (and energy conversion) from a microscopic perspective. First we focus on understanding why classical laws (i.e. Fourier Law) are what they are and what are their
Electroacoustic phenomena arise when ultrasound propagates through a fluid containing ions. The associated particle motion generates electric signals because ions have electric charge. This coupling between ultrasound and electric field is called electroacoustic phenomena. The fluid might be a simple Newtonian liquid, or complex heterogeneous dispersion, emulsion or even a porous body. There are several different electroacoustic effects depending on the nature of the fluid.
vignette|350px|Concentration ionique et différence de potentiel en fonction de la distance à la surface d'une particule en solution. Le potentiel zêta (ou potentiel électrocinétique zêta) représente la différence de potentiel entre la surface de la particule, recouverte d’ions opposés et solidement fixés, et le point de neutralité. Le potentiel zêta est un bon indicateur des interactions entre particules et donc de la stabilité des colloïdes tels que les émulsions (selon la théorie DLVO développée par Boris Derjaguin, Lev Landau, Evert Verwey et Theodoor Overbeek en 1940 qui propose que la stabilité des particules en suspension dépend d’un potentiel d’interaction total).
Explore les phénomènes électrocinétiques, y compris le mouvement des particules colloïdales et le modèle double couche diffuse dans les séparations chimiques.