<p>In this paper, electro-osmotic flow of a Newtonian liquid solution over superhydrophobic transverse grooves is numerically studied. Uniform charge is imposed on the solid surface along the ribs while the liquid–gas interface along the grooves are taken to be uncharged. With inhomogeneous wall charged condition imposed, the normalized axial flow attained is smaller as compared with that of homogeneous charged smooth wall. This is principally owing to the absent of structured layer of ions along the liquid–gas interface that is desired to drive the electro-osmotic flow. Despite the weaker axial flow, the presence of transverse superhydrophobic grooves results in the substantial vertical flow, with normalized magnitude <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40430_2025_5429_Article_IEq1.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="43" /> </InlineMediaObject> <EquationSource Format="TEX">$v/{u}_{sh}$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>v</mi> <mo stretchy="false">/</mo> <msub> <mi>u</mi> <mrow> <mi mathvariant="italic">sh</mi> </mrow> </msub> </mrow> </math></EquationSource> </InlineEquation> of 0.05. The staggered arrangement of grooves and ribs is found to yield substantial vertical flow as compared with that of in-line counterpart. Apart from the superhydrophobic grooves arrangement, the alteration of the axial and vertical flows is also dependent on the relative size of the superhydrophobic groove structure and the ratio of the channel height to the electric double layer thickness. With the superhydrophobic grooves of <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40430_2025_5429_Article_IEq2.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="43" /> </InlineMediaObject> <EquationSource Format="TEX">$\Lambda =2$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi mathvariant="normal">Λ</mi> <mo>=</mo> <mn>2</mn> </mrow> </math></EquationSource> </InlineEquation>, the normalized vertical flow of 0.15 can be attained along the flow centerline.</p>

Electro-osmotic flow in channel patterned with staggered superhydrophobic grooves

期刊论文
发表日期：

2025年2月14日

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Mei Jing,
Kok Hwa Yu,
Mohd Sharizal Abdul Aziz,
Wei Shyang Chang

摘要

In this paper, electro-osmotic flow of a Newtonian liquid solution over superhydrophobic transverse grooves is numerically studied. Uniform charge is imposed on the solid surface along the ribs while the liquid–gas interface along the grooves are taken to be uncharged. With inhomogeneous wall charged condition imposed, the normalized axial flow attained is smaller as compared with that of homogeneous charged smooth wall. This is principally owing to the absent of structured layer of ions along the liquid–gas interface that is desired to drive the electro-osmotic flow. Despite the weaker axial flow, the presence of transverse superhydrophobic grooves results in the substantial vertical flow, with normalized magnitude $v/{u}_{sh}$ $v / u_{sh}$ of 0.05. The staggered arrangement of grooves and ribs is found to yield substantial vertical flow as compared with that of in-line counterpart. Apart from the superhydrophobic grooves arrangement, the alteration of the axial and vertical flows is also dependent on the relative size of the superhydrophobic groove structure and the ratio of the channel height to the electric double layer thickness. With the superhydrophobic grooves of $\Lambda =2$ $Λ = 2$ , the normalized vertical flow of 0.15 can be attained along the flow centerline.