Numerical Analysis of Convective Mass Transfer during Multi-Droplet Impingement on a Structured Surface in the Presence of an Adhered Liquid Film—An Application to Spray Etching of PCBs
Multi-droplet impingement is a fundamental aspect inherent to all kinds of technical spray processes which typically aim at enhancing the convective exchange of reagents or heat at the impinged surface. In this paper, the impingement of multiple droplets onto a structured surface is investigated by...
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| Format: | Article |
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MDPI AG
2023-06-01
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| Series: | Fluids |
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| Online Access: | https://www.mdpi.com/2311-5521/8/6/180 |
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| author | Werner Eßl Georg Reiss Peter Raninger Werner Ecker Nadine Körbler Eva Gerold Helmut Antrekowitsch Jolanta Klocek Thomas Krivec |
| author_facet | Werner Eßl Georg Reiss Peter Raninger Werner Ecker Nadine Körbler Eva Gerold Helmut Antrekowitsch Jolanta Klocek Thomas Krivec |
| author_sort | Werner Eßl |
| collection | DOAJ |
| description | Multi-droplet impingement is a fundamental aspect inherent to all kinds of technical spray processes which typically aim at enhancing the convective exchange of reagents or heat at the impinged surface. In this paper, the impingement of multiple droplets onto a structured surface is investigated by a comprehensive CFD model, which resolves the dynamics of the individual droplets and the film on a micro-scale level based on the Volume of Fluid (VOF) method. The considered surface topology includes cavities and is typical for protective masks used in the spray etching of Printed Circuit Boards (PCBs). The agitation of the liquid film in terms of the convective mass transfer rates across virtual horizontal evaluation planes is studied and the influence of film height and droplet impaction velocity is elaborated. Passive tracer tracking is employed to investigate the release and re-entrainment of fluid at the surface cavities. Two modes of mass exchange between the cavities and the main flow upon droplet impingement are identified, which are central inflow accompanied by lateral outflow (1) and lateral inflow with outflow at the opposing side (2). A statistical analysis of the allocation of tracer particles shows that high impaction velocities and low film heights correlate with an enhanced decay of tracer particles within the cavities. The susceptibility to re-entrainment is also reduced by high impaction velocities, whereas increased film heights are found to promote re-entrainment. |
| first_indexed | 2024-03-11T02:29:04Z |
| format | Article |
| id | doaj.art-b4c74c60113646ae8ca7e6ba40181b48 |
| institution | Directory Open Access Journal |
| issn | 2311-5521 |
| language | English |
| last_indexed | 2024-03-11T02:29:04Z |
| publishDate | 2023-06-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Fluids |
| spelling | doaj.art-b4c74c60113646ae8ca7e6ba40181b482023-11-18T10:23:23ZengMDPI AGFluids2311-55212023-06-018618010.3390/fluids8060180Numerical Analysis of Convective Mass Transfer during Multi-Droplet Impingement on a Structured Surface in the Presence of an Adhered Liquid Film—An Application to Spray Etching of PCBsWerner Eßl0Georg Reiss1Peter Raninger2Werner Ecker3Nadine Körbler4Eva Gerold5Helmut Antrekowitsch6Jolanta Klocek7Thomas Krivec8Materials Center Leoben Forschung GmbH, Roseggerstrasse 12, 8700 Leoben, AustriaMaterials Center Leoben Forschung GmbH, Roseggerstrasse 12, 8700 Leoben, AustriaMaterials Center Leoben Forschung GmbH, Roseggerstrasse 12, 8700 Leoben, AustriaMaterials Center Leoben Forschung GmbH, Roseggerstrasse 12, 8700 Leoben, AustriaChair of Nonferrous Metallurgy, Montanuniversitaet Leoben, Franz-Josef-Strasse 18, 8700 Leoben, AustriaChair of Nonferrous Metallurgy, Montanuniversitaet Leoben, Franz-Josef-Strasse 18, 8700 Leoben, AustriaChair of Nonferrous Metallurgy, Montanuniversitaet Leoben, Franz-Josef-Strasse 18, 8700 Leoben, AustriaAustria Technologie & Systemtechnik (AT&S) Aktiengesellschaft, Fabriksgasse 13, 8700 Leoben, AustriaAustria Technologie & Systemtechnik (AT&S) Aktiengesellschaft, Fabriksgasse 13, 8700 Leoben, AustriaMulti-droplet impingement is a fundamental aspect inherent to all kinds of technical spray processes which typically aim at enhancing the convective exchange of reagents or heat at the impinged surface. In this paper, the impingement of multiple droplets onto a structured surface is investigated by a comprehensive CFD model, which resolves the dynamics of the individual droplets and the film on a micro-scale level based on the Volume of Fluid (VOF) method. The considered surface topology includes cavities and is typical for protective masks used in the spray etching of Printed Circuit Boards (PCBs). The agitation of the liquid film in terms of the convective mass transfer rates across virtual horizontal evaluation planes is studied and the influence of film height and droplet impaction velocity is elaborated. Passive tracer tracking is employed to investigate the release and re-entrainment of fluid at the surface cavities. Two modes of mass exchange between the cavities and the main flow upon droplet impingement are identified, which are central inflow accompanied by lateral outflow (1) and lateral inflow with outflow at the opposing side (2). A statistical analysis of the allocation of tracer particles shows that high impaction velocities and low film heights correlate with an enhanced decay of tracer particles within the cavities. The susceptibility to re-entrainment is also reduced by high impaction velocities, whereas increased film heights are found to promote re-entrainment.https://www.mdpi.com/2311-5521/8/6/180Volume of Fluiddroplet impingementstructured surfacespray etchingconvective mass transfer |
| spellingShingle | Werner Eßl Georg Reiss Peter Raninger Werner Ecker Nadine Körbler Eva Gerold Helmut Antrekowitsch Jolanta Klocek Thomas Krivec Numerical Analysis of Convective Mass Transfer during Multi-Droplet Impingement on a Structured Surface in the Presence of an Adhered Liquid Film—An Application to Spray Etching of PCBs Fluids Volume of Fluid droplet impingement structured surface spray etching convective mass transfer |
| title | Numerical Analysis of Convective Mass Transfer during Multi-Droplet Impingement on a Structured Surface in the Presence of an Adhered Liquid Film—An Application to Spray Etching of PCBs |
| title_full | Numerical Analysis of Convective Mass Transfer during Multi-Droplet Impingement on a Structured Surface in the Presence of an Adhered Liquid Film—An Application to Spray Etching of PCBs |
| title_fullStr | Numerical Analysis of Convective Mass Transfer during Multi-Droplet Impingement on a Structured Surface in the Presence of an Adhered Liquid Film—An Application to Spray Etching of PCBs |
| title_full_unstemmed | Numerical Analysis of Convective Mass Transfer during Multi-Droplet Impingement on a Structured Surface in the Presence of an Adhered Liquid Film—An Application to Spray Etching of PCBs |
| title_short | Numerical Analysis of Convective Mass Transfer during Multi-Droplet Impingement on a Structured Surface in the Presence of an Adhered Liquid Film—An Application to Spray Etching of PCBs |
| title_sort | numerical analysis of convective mass transfer during multi droplet impingement on a structured surface in the presence of an adhered liquid film an application to spray etching of pcbs |
| topic | Volume of Fluid droplet impingement structured surface spray etching convective mass transfer |
| url | https://www.mdpi.com/2311-5521/8/6/180 |
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