Nanofluidics

An Introduction

Zhigang Li

• Publisher: CRC Press
• Year: 2018
• Print ISBN:
  9781138035515
• eBook ISBN:
  9781351969567
• Topic: Physical Sciences
• Subtopic: Analytic Chemistry

This book provides an introduction to nanofluidics in a simple manner and can be easily followed by senior undergraduate students, graduate students, and other researchers who have some background in fluid mechanics. The book covers the main topics about the fundamentals of nanofluidics and how it differs from classic fluid mechanics. It also describes the methodologies of nanofluidics, including numerical approaches, e.g., molecular dynamics simulation and experimental techniques. Fundamental physics and new phenomena in nanofluidics are the major concerns of this book.

The author goes on to discuss nanocofinements and the parameters that affect the fluid dynamics at the nanoscale and make flow analysis complex. These parameters accommodate rich, new flow phenomena that may not be observed at the macro- and microscale. Although not all of the new phenomena will find widespread applications, the physics underlying these new phenomena may offer insights for other fields. This is one of the reasons why this book emphasizes the mechanisms of various flow fashions.

• Explores the unique characteristics of nanoscale flows and related properties
• Reviews the latest research of nanoscale ion transport and its applications
• Discusses the fluid flows in nanoconfinements in a unique manner based on the author's original research
• Incorporates important applications of nanofluidics throughout.

Chapter 1 Fundamentals of classic fluid mechanics

1.1 Introduction

Nanofluidics is concerned with fluid flows in nanoscale confinements. It can be quite different from the classic fluid transport in macro-systems. The difference is mainly caused by molecular interactions, which cause changes in fluid properties and lead to new transport phenomena. Although molecular interactions play important roles at the nanoscale, many ideas at the macroscale are valid. Therefore, before a new journey to the nanoscale, it is necessary to review the classic fluid mechanics. Readers who are familiar with the classic fluid mechanics and electrokinetics can skip this chapter and move to Chapter 2 directly. Further detailed information about the classic theories can be found in standard textbooks on fluid mechanics and electrokinetics.

1.2 What is a fluid

In the classic fluid mechanics, a fluid is defined as a substance that deforms continuously under a shearing stress of any magnitude. This definition is clear and presents a practical base for telling whether a substance is a fluid or not. Another approach to distinguish fluids from solids is to look into the motion of molecules or atoms. At the molecular scale, for solids, all the atoms are vibrating around and cannot move far away from their equilibrium positions, as illustrated in Figure 1.1a. Fluid molecules, however, can move freely in available space due to the weak molecular interactions (Figure 1.1b). Such difference between fluids and solids can be reflected in the mean square displacement (MSD) of molecules, which is defined as

〈Δr2(t)〉=∑i=1N[ri(t)−ri(0)]2/N(1.1)

where r is the position variable, t is time, and N is the total number of molecules. Since MSD is a measure of relative positions of atoms, it is bounded for solids with respect to time. For fluids, however, it can be shown that the MSD is proportional to time (Reif, 1985). Therefore, fluids and solids can be distinguished based on the dependence of the MSD on time, as demonstrated in Figure 1.2. Practically, Equation 1.1 may not be a good way to characterize a substance because it is difficult to probe the motion of atoms. However, in nanofluidics, MSD is useful in studying the phase change of materials because it can be easily obtained in numerical simulations, as will be discussed later.

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Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Dedication Page
• Table of Contents
• Preface
• Author
• 1 Fundamentals of classic fluid mechanics
• 2 Introduction to nanofluidics
• 3 Molecular dynamics simulation
• 4 Nanofabrication
• 5 Nanoscale capillarity
• 6 Nanoscale simple fluid flows
• 7 External flows
• 8 Nanoscale electrokinetic phenomena
• Appendix A
• Appendix B
• Appendix C
• Index