TY - JOUR

T1 - Diffusion equations based on generalized continuum mechanics and numerical analysis

AU - Yokozuka, T.

AU - Funasako, T.

AU - Shimada, H.

AU - Shizawa, K.

AU - Takahashi, K.

PY - 1996

Y1 - 1996

N2 - We propose that an increasing value in entropy inequality is not a local value of entropy but an average value in a mesodomain. From this standpoint, new balance equations are obtained by applying the concept of generalized continuum mechanics to mass transfer. In the present paper, it is clarified that the influence of microscopic gradient of mass concentration should be included in Fick's first law and Fourier's law. Even if thermal effects on diffusion are neglected, the diffusion equations obtained here are simultaneous differential equations with two undetermined values, which coincide with the conventional diffusion equation in a special case. The conventional diffusion equation describing infinite velocity of propagation associated with diffusion entails a contradiction. The velocity of propagation defined here is shown in the results of numerical analysis for an extreme initial state. Consequently, it is indicated that the present theory gives an acceptable solution to the above problem of the conventional theory.

AB - We propose that an increasing value in entropy inequality is not a local value of entropy but an average value in a mesodomain. From this standpoint, new balance equations are obtained by applying the concept of generalized continuum mechanics to mass transfer. In the present paper, it is clarified that the influence of microscopic gradient of mass concentration should be included in Fick's first law and Fourier's law. Even if thermal effects on diffusion are neglected, the diffusion equations obtained here are simultaneous differential equations with two undetermined values, which coincide with the conventional diffusion equation in a special case. The conventional diffusion equation describing infinite velocity of propagation associated with diffusion entails a contradiction. The velocity of propagation defined here is shown in the results of numerical analysis for an extreme initial state. Consequently, it is indicated that the present theory gives an acceptable solution to the above problem of the conventional theory.

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U2 - 10.1299/kikaib.62.1977

DO - 10.1299/kikaib.62.1977

M3 - Article

AN - SCOPUS:0030148943

SN - 0387-5016

VL - 62

SP - 1977

EP - 1983

JO - Nippon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B

JF - Nippon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B

IS - 597

ER -