Abstract— <p>A structural rheological model is used to study a thixotropic disperse system of silica in oil. The model includes a kinetic equation delineating the formation and destruction of particle aggregates and a rheological equation with a structural parameter (the number of aggregated particles within a unit volume). The equilibrium plastic flow corresponding to experimental flow curves is considered. The coefficients of the rheological equation are determined. The transition upon a stepwise rise in the shear rate from <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11504_2025_6086_Article_IEq1.gif" Format="GIF" Height="17" Rendition="HTML" Resolution="72" Type="Linedraw" Width="17" /> </InlineMediaObject> <EquationSource Format="TEX">\({{\dot {\gamma }}_{1}}\)</EquationSource>  </InlineEquation> to <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11504_2025_6086_Article_IEq2.gif" Format="GIF" Height="17" Rendition="HTML" Resolution="72" Type="Linedraw" Width="17" /> </InlineMediaObject> <EquationSource Format="TEX">\({{\dot {\gamma }}_{2}}\)</EquationSource>  </InlineEquation> is regarded as a transition from one equilibrium state of flow to another state through a certain non-equilibrium state of flow. The coefficient of deviating from equilibrium is introduced, and its temporal dependence <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11504_2025_6086_Article_IEq3.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="29" /> </InlineMediaObject> <EquationSource Format="TEX">\(\xi (t)\)</EquationSource>  </InlineEquation> is calculated using exponential functions. The limit value of <InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11504_2025_6086_Article_IEq4.gif" Format="GIF" Height="17" Rendition="HTML" Resolution="72" Type="Linedraw" Width="16" /> </InlineMediaObject> <EquationSource Format="TEX">\({{\xi }_{0}}\)</EquationSource>  </InlineEquation> is determined, and transition dependences <InlineEquation ID="IEq5"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11504_2025_6086_Article_IEq5.gif" Format="GIF" Height="21" Rendition="HTML" Resolution="72" Type="Linedraw" Width="47" /> </InlineMediaObject> <EquationSource Format="TEX">\({{\tau }^{{1/2}}}(t)\)</EquationSource>  </InlineEquation> are approximated.</p>

Rheology of Thixotropic Dispersions: Transient Phenomena upon a Rising Shear Rate

期刊论文
发表日期：

2025年3月1日

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V. N. Matveenko,
E. A. Kirsanov

摘要

Abstract—

A structural rheological model is used to study a thixotropic disperse system of silica in oil. The model includes a kinetic equation delineating the formation and destruction of particle aggregates and a rheological equation with a structural parameter (the number of aggregated particles within a unit volume). The equilibrium plastic flow corresponding to experimental flow curves is considered. The coefficients of the rheological equation are determined. The transition upon a stepwise rise in the shear rate from \({{\dot {\gamma }}_{1}}\) to \({{\dot {\gamma }}_{2}}\) is regarded as a transition from one equilibrium state of flow to another state through a certain non-equilibrium state of flow. The coefficient of deviating from equilibrium is introduced, and its temporal dependence \(\xi (t)\) is calculated using exponential functions. The limit value of \({{\xi }_{0}}\) is determined, and transition dependences \({{\tau }^{{1/2}}}(t)\) are approximated.