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arXiv 2603.03533math.APmath-phmath.MP
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简单反应-对流-扩散方程的脉冲响应分析

Pulse-response analysis of a simple reaction-advection-diffusion equation

Washington University(华盛顿大学);McKelvey School of Engineering, Washington University(华盛顿大学麦凯利工程学院)

Jiasong Zhu, Renato Feres, Donsub Rim, Gregory Yablonsky

AI总结:

本文通过分析反应-对流-扩散方程的脉冲响应,研究了对流速度对化学活性的影响,并提出通过比值确定化学活性的方法。

摘要:

我们从脉冲响应研究的角度对一个反应-对流-扩散(RAD)方程进行了详细分析,特别关注对流速度的影响。我们的边界值问题是一个数学模型,描述了一个狭窄的反应管,其中一种反应气体脉冲被注入一端,而反应产物和未反应气体的混合物从另一端流出。通过解析方法,获得了诸如流量时刻和峰值特征等出口流量性质,这些性质作为佩克莱数的函数。标准传输曲线的描述——包括扩散和对流但无反应——可以作为进一步表征化学活性的基准。在这里,我们对一级不可逆反应进行了这种表征。我们的主要观察之一是,化学活性可以通过反应存在时的出口流量曲线与标准传输曲线的比值轻易获得。

英文摘要:

We analyze a reaction-advection-diffusion (RAD) equation arising in pulse-response studies of transport and reaction in a narrow reactor tube. A short pulse of gas is injected near one end of the reactor, while unreacted gas and reaction products are detected at the outlet. Particular attention is given to the effect of a constant axial advection velocity as a minimal extension of the standard diffusion model. For a single pulse, we obtain analytical expressions for the exit-flow response and for experimentally accessible characteristics, including its moments and peak properties, as functions of the Péclet number and the reaction rate. The corresponding diffusion-advection model without reaction defines a standard transport curve that may be used as a baseline for identifying chemical activity. For a first-order irreversible reaction, the reactive and nonreactive exit-flow curves satisfy a simple exponential factorization, allowing the reaction rate to be extracted directly from their ratio. We also extend the single-pulse analysis to a uniform periodic train of pulses. Using Poisson summation, we derive explicit expressions for the Fourier coefficients of the asymptotic periodic exit flow and relate them to the Laplace transform and moments of the single-pulse response. Finally, a stochastic interpretation in terms of reflected diffusion, first-passage times, and exponential killing provides probabilistic meaning for several of the analytical results and unifies the single-pulse, periodic-response, and reaction aspects of the model.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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