<p>Active flow control offers promising solutions for enhancing the performance of microfluidics. Magnetic fields can affect micro-scale devices' heat transfer characteristics and flow shape, affecting system performance and reliability. Curved channels are key components of thermal and biomedical systems and are crucial for integrating and miniaturizing microsystems. With this point of view, this numerical study investigates the simultaneous effects of curvature and magnetic field on the thermo-hydraulic behavior of microchannels in engineering and medical applications. Several local and average parameters were examined to evaluate the volumetric and surface behavior of the bio-hybrid nanofluid (Cu + CuO/Blood) in the studied microchannels. Numerical results show that if a magnetic field is placed in a specific direction and with particular strength in the curved microchannel, the resulting magnetic force can eliminate the effects of curvature, including the secondary flow. Therefore, the surface and volumetric parameters of flow and heat transfer, including the heat transfer coefficient, friction coefficient, and pressure drop, become similar to those of the flow in a straight microchannel. At Reynolds number (<InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10973_2024_13852_Article_IEq1.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="24" /> </InlineMediaObject> <EquationSource Format="TEX">$Re$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi mathvariant="italic">Re</mi> </mrow> </math></EquationSource> </InlineEquation>) 450, the heat transfer coefficient in circular and curved microchannels without a magnetic field deviates by 113.8% and 87.1%, respectively, compared to a straight microchannel. Increasing the Hartmann number (<InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10973_2024_13852_Article_IEq2.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="28" /> </InlineMediaObject> <EquationSource Format="TEX">$Ha$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi mathvariant="italic">Ha</mi> </mrow> </math></EquationSource> </InlineEquation>) up to 30 can reduce the maximum deviation of microchannels to about 1%. Therefore, the values of the corresponding parameters eventually converge and show good agreement by reaching a critical <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10973_2024_13852_Article_IEq2.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="28" /> </InlineMediaObject> <EquationSource Format="TEX">$Ha$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi mathvariant="italic">Ha</mi> </mrow> </math></EquationSource> </InlineEquation>. Overall, this study underscores the potential of passive control of unwanted mixing in microfluidics devices.</p>

Effect of magnetic field on the thermal and hydraulic behavior of biological hybrid nanofluid flow in curved microchannels

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发表日期：

2025年1月15日

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M. Gharehkhani,
S. Dinarvand,
M. R. Hajmohammadi

摘要

Active flow control offers promising solutions for enhancing the performance of microfluidics. Magnetic fields can affect micro-scale devices' heat transfer characteristics and flow shape, affecting system performance and reliability. Curved channels are key components of thermal and biomedical systems and are crucial for integrating and miniaturizing microsystems. With this point of view, this numerical study investigates the simultaneous effects of curvature and magnetic field on the thermo-hydraulic behavior of microchannels in engineering and medical applications. Several local and average parameters were examined to evaluate the volumetric and surface behavior of the bio-hybrid nanofluid (Cu + CuO/Blood) in the studied microchannels. Numerical results show that if a magnetic field is placed in a specific direction and with particular strength in the curved microchannel, the resulting magnetic force can eliminate the effects of curvature, including the secondary flow. Therefore, the surface and volumetric parameters of flow and heat transfer, including the heat transfer coefficient, friction coefficient, and pressure drop, become similar to those of the flow in a straight microchannel. At Reynolds number ( $Re$ $Re$ ) 450, the heat transfer coefficient in circular and curved microchannels without a magnetic field deviates by 113.8% and 87.1%, respectively, compared to a straight microchannel. Increasing the Hartmann number ( $Ha$ $Ha$ ) up to 30 can reduce the maximum deviation of microchannels to about 1%. Therefore, the values of the corresponding parameters eventually converge and show good agreement by reaching a critical $Ha$ $Ha$ . Overall, this study underscores the potential of passive control of unwanted mixing in microfluidics devices.