




版權(quán)說明:本文檔由用戶提供并上傳,收益歸屬內(nèi)容提供方,若內(nèi)容存在侵權(quán),請進(jìn)行舉報(bào)或認(rèn)領(lǐng)
文檔簡介
1、Drop Impact and Spreading on Surfaces of Variable Wettability,J.E Sprittles Y.D. Shikhmurzaev,Bonn 2007,Swansea 2007,Motivation,Drop impact and spreading occurs in many industrial processes. 100 million inkjet printers sold yearly. NEW: Inkjet printing of electronic circuits. Why study the old probl
2、em of drops spreading on surfaces?,Swansea 2007,Worthington 1876 First Experiments,Swansea 2007,Worthingtons Sketches,Millimetre sized drops of milk on smoked glass.,Swansea 2007,Modern Day Experiments (mm drops of water),Courtesy of Romain Rioboo,Swansea 2007,Xu et al 03 Drops dont splash at the to
3、p of Everest!,Swansea 2007,Renardy 03 et al - Pyramidal Drops,Impact of oscillating water drops on super hydrophobic substrates,1,2,3,4,Swansea 2007,The Simplest Problem,How does a drops behaviour depend on: fluid properties, drop speed, drop size,. etc?,Spread Factor,Apex Height,Contact Angle,a,Swa
4、nsea 2007,The Contact Angle,In equilibrium the angle defines the wettability of a solid-liquid combination. How should we describe it in a dynamic situation?,More Wettable (Hydrophilic),Less Wettable (Hydrophobic),Solid 1,Solid 2,Swansea 2007,Modelling of Drop Impact and Spreading Phenomena,The Movi
5、ng Contact Line Problem Conventional Approaches and their Drawbacks The Shikhmurzaev Model,Swansea 2007,The Moving Contact Line Problem,Liquid,Inviscid Gas,Contact line,Contact angle,Solid,Swansea 2007,The Moving Contact Line Problem,No-Slip Impermeability,Kinematic condition Dynamic condition,Navie
6、r-Stokes Continuity,Contact angle prescribed,No solution!,Swansea 2007,The Conventional Approach,These are treated separately by: 1)Modifying the no-slip condition near the Contact Line (CL) to allow slip, e.g. 2)Prescribing the Contact Angle as a function of various parameters, e.g.,One must: 1)All
7、ow a solution to be obtained. 2)Describe the macroscopic contact angle.,Swansea 2007,Experiments Show This Is Wrong,Can one describe the contact angle as a function of the parameters? “There is no universal expression to relate contact angle with contact line speed”. (Bayer and Megaridis 06) “There
8、is no general correlation of the dynamic contact angle as a function of surface characteristics, droplet fluid and diameter and impact velocity.” (Sikalo et al 02),Swansea 2007,As in Curtain Coating,Used to industrially coat materials. Conventional models: Fixed substrate speed = Unique contact angl
9、e,Swansea 2007,Hydrodynamic Assist of Dynamic Wetting,The contact angle depends on the flow field.,See: Blake et al 1994, Blake et al 1999, Clarke et al 2006,Swansea 2007,Angle Also Dependent On The Geometry: Flow Through a Channel,The contact angle is dependent on d and U. (Ngan surface velocity, a
10、nd surface density, .,Equation of State,Input of Wettability,Swansea 2007,The Shikhmurzaev Model:Constant Wettability,Bulk,Interfacial Layer: For Visualisation Only. In the continuum limit.,If then we have Navier Slip,Swansea 2007,Solid-Liquid Boundary Conditions Shikhmurzaev Equations,Bulk,Tangenti
11、al velocity,Surface velocity,Solid facing side of interface: No-slip,Layer is for VISUALISATION only. In the continuum limit,Swansea 2007,Solid-Liquid Boundary Conditions Shikhmurzaev Equations,Bulk,Continuity of surface mass,Normal velocity,Solid facing side of interface: Impermeability,Layer is fo
12、r VISUALISATION only. In the continuum limit,Swansea 2007,Problem Formulation,2D, steady flow of an incompressible, viscous, Newtonian fluid over a stationary flat solid surface (y=0), driven by a shear in the far field. Bulk Navier Stokes equations:,Boundary Conditions Shear flow in the far field,
13、which, using gives:,Swansea 2007,Results - Streamlines,Consider solid 1 (x0). Coupled, nonlinear PDEs were solved using the finite element method.,Swansea 2007,Results Different Solid Combinations,Consider different solid combinations.,Swansea 2007,Results Size of The Effect,Consider the normal flux
14、 out of the interface, per unit time, J. We find:,The constant of proportionality is dependent on the fluid and the magnitude of the shear applied.,Swansea 2007,Results - The Generators of Slip,Variations in slip are mainly caused by variations in surface tension.,1) Deviation of shear stress on the
15、 interface from equilibrium. 2) Surface tension gradients.,Swansea 2007,Periodically Patterned Surface,Consider Solid 1 More Wettable. Consider a=1 - Strips Have Equal Width.,Swansea 2007,Results - Streamlines,Solid 2 less wettable,Qualitative agreement,Swansea 2007,Results Velocity Profiles,Tangent
16、ial (slip) velocity varies around its equilibrium value of u=9.8.,Fluxes are both in and out of the interfacial layer. Overall mass is conserved.,Swansea 2007,Further Work,Compare results with molecular dynamics simulations. Devise experiments to test predictions. Fully investigate periodic case. Si
17、ngle transition investigation is in: Sprittles Strm et al. 1990; Fermigier : Burley , , : Strm et al. 1990),It has been shown that the theory is in good agreement with all experimental data published in the literature.,Swansea 2007,Mechanism of Relaxation,Comparison of the theory with experiments on fluids with different vi
溫馨提示
- 1. 本站所有資源如無特殊說明,都需要本地電腦安裝OFFICE2007和PDF閱讀器。圖紙軟件為CAD,CAXA,PROE,UG,SolidWorks等.壓縮文件請下載最新的WinRAR軟件解壓。
- 2. 本站的文檔不包含任何第三方提供的附件圖紙等,如果需要附件,請聯(lián)系上傳者。文件的所有權(quán)益歸上傳用戶所有。
- 3. 本站RAR壓縮包中若帶圖紙,網(wǎng)頁內(nèi)容里面會(huì)有圖紙預(yù)覽,若沒有圖紙預(yù)覽就沒有圖紙。
- 4. 未經(jīng)權(quán)益所有人同意不得將文件中的內(nèi)容挪作商業(yè)或盈利用途。
- 5. 人人文庫網(wǎng)僅提供信息存儲(chǔ)空間,僅對(duì)用戶上傳內(nèi)容的表現(xiàn)方式做保護(hù)處理,對(duì)用戶上傳分享的文檔內(nèi)容本身不做任何修改或編輯,并不能對(duì)任何下載內(nèi)容負(fù)責(zé)。
- 6. 下載文件中如有侵權(quán)或不適當(dāng)內(nèi)容,請與我們聯(lián)系,我們立即糾正。
- 7. 本站不保證下載資源的準(zhǔn)確性、安全性和完整性, 同時(shí)也不承擔(dān)用戶因使用這些下載資源對(duì)自己和他人造成任何形式的傷害或損失。
最新文檔
- 詐騙對(duì)公賬戶管理辦法
- 廣電行業(yè)統(tǒng)計(jì)管理辦法
- 福建建設(shè)動(dòng)態(tài)管理辦法
- 肥胖課件下載
- 高二數(shù)學(xué)導(dǎo)數(shù)數(shù)學(xué)試卷
- 分班考數(shù)學(xué)試卷
- 二中廣雅初三數(shù)學(xué)試卷
- 二數(shù)下數(shù)學(xué)試卷
- 廣安市2024年二診數(shù)學(xué)試卷
- 2025年04月浙江省衢州市衢江區(qū)衛(wèi)生健康系統(tǒng)招引高層次緊缺人才27人筆試歷年專業(yè)考點(diǎn)(難、易錯(cuò)點(diǎn))附帶答案詳解
- TCCES 44-2024 老舊房屋結(jié)構(gòu)安全監(jiān)測技術(shù)標(biāo)準(zhǔn)
- 廣東省2025年普通高等學(xué)校招生全國統(tǒng)一考試模擬測試(一)物理試題及答案
- 2024年汽車維修工技能理論考試題庫含答案(滿分必刷)
- 腸息肉病人護(hù)理查房
- 2025年云南紅河弘毅農(nóng)業(yè)發(fā)展限責(zé)任公司第一批員工招聘10人自考難、易點(diǎn)模擬試卷(共500題附帶答案詳解)
- 林下中藥材種植項(xiàng)目可行性研究報(bào)告
- 計(jì)量知識(shí)宣傳培訓(xùn)課件
- 汽車4s店管理制度
- 電腦常見故障維修與電腦保養(yǎng)課件
- 電商平臺(tái)商家入駐流程及風(fēng)險(xiǎn)控制標(biāo)準(zhǔn)
- 2025年上半年山東省濟(jì)南市事業(yè)單位筆試易考易錯(cuò)模擬試題(共500題)試卷后附參考答案
評(píng)論
0/150
提交評(píng)論