Phase transitions of fluids in heterogeneous pores
We study phase behaviour of a model fluid confined between two unlike parallel walls in the presence of long range (dispersion) forces. Predictions obtained from macroscopic (geometric) and mesoscopic arguments are compared with numerical solutions of a non-local density functional theory. Two capil...
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Інститут фізики конденсованих систем НАН України
2016
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| Schriftenreihe: | Condensed Matter Physics |
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| Zitieren: | Phase transitions of fluids in heterogeneous pores / A. Malijevský // Condensed Matter Physics. — 2016. — Т. 19, № 1. — С. 13604: 1–18. — Бібліогр.: 27 назв. — англ. |
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We study phase behaviour of a model fluid confined between two unlike parallel walls in the presence of long range (dispersion) forces. Predictions obtained from macroscopic (geometric) and mesoscopic arguments are compared with numerical solutions of a non-local density functional theory. Two capillary models are considered. For a capillary comprising two (differently) adsorbing walls we show that simple geometric arguments lead to the generalized Kelvin equation locating very accurately capillary condensation, provided both walls are only partially wet. If at least one of the walls is in complete wetting regime, the Kelvin equation should be modified by capturing the effect of thick wetting films by including Derjaguin's correction. Within the second model, we consider a capillary formed of two competing walls, so that one tends to be wet and the other dry. In this case, an interface localized-delocalized transition occurs at bulk two-phase coexistence and a temperature T*(L) depending on the pore width L. A mean-field analysis shows that for walls exhibiting first-order wetting transition at a temperature Tw, Ts > T*(L) > Tw, where the spinodal temperature Ts can be associated with the prewetting critical temperature, which also determines a critical pore width below which the interface localized-delocalized transition does not occur. If the walls exhibit critical wetting, the transition is shifted below Tw and for a model with the binding potential W(l)=A(T)l⁻²+B(T)l⁻³+..., where l is the location of the liquid-gas interface, the transition can be characterized by a dimensionless parameter κ=B/(AL), so that the fluid configuration with delocalized interface is stable in the interval between κ=-2/3 and κ ~ -0.23. |
| format |
Article |
| author |
Malijevský, A. |
| spellingShingle |
Malijevský, A. Phase transitions of fluids in heterogeneous pores Condensed Matter Physics |
| author_facet |
Malijevský, A. |
| author_sort |
Malijevský, A. |
| title |
Phase transitions of fluids in heterogeneous pores |
| title_short |
Phase transitions of fluids in heterogeneous pores |
| title_full |
Phase transitions of fluids in heterogeneous pores |
| title_fullStr |
Phase transitions of fluids in heterogeneous pores |
| title_full_unstemmed |
Phase transitions of fluids in heterogeneous pores |
| title_sort |
phase transitions of fluids in heterogeneous pores |
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Інститут фізики конденсованих систем НАН України |
| publishDate |
2016 |
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http://dspace.nbuv.gov.ua/handle/123456789/155796 |
| citation_txt |
Phase transitions of fluids in heterogeneous pores / A. Malijevský // Condensed Matter Physics. — 2016. — Т. 19, № 1. — С. 13604: 1–18. — Бібліогр.: 27 назв. — англ. |
| series |
Condensed Matter Physics |
| work_keys_str_mv |
AT malijevskya phasetransitionsoffluidsinheterogeneouspores |
| first_indexed |
2025-07-14T08:01:51Z |
| last_indexed |
2025-07-14T08:01:51Z |
| _version_ |
1837608585804120064 |
| spelling |
irk-123456789-1557962019-06-18T01:27:23Z Phase transitions of fluids in heterogeneous pores Malijevský, A. We study phase behaviour of a model fluid confined between two unlike parallel walls in the presence of long range (dispersion) forces. Predictions obtained from macroscopic (geometric) and mesoscopic arguments are compared with numerical solutions of a non-local density functional theory. Two capillary models are considered. For a capillary comprising two (differently) adsorbing walls we show that simple geometric arguments lead to the generalized Kelvin equation locating very accurately capillary condensation, provided both walls are only partially wet. If at least one of the walls is in complete wetting regime, the Kelvin equation should be modified by capturing the effect of thick wetting films by including Derjaguin's correction. Within the second model, we consider a capillary formed of two competing walls, so that one tends to be wet and the other dry. In this case, an interface localized-delocalized transition occurs at bulk two-phase coexistence and a temperature T*(L) depending on the pore width L. A mean-field analysis shows that for walls exhibiting first-order wetting transition at a temperature Tw, Ts > T*(L) > Tw, where the spinodal temperature Ts can be associated with the prewetting critical temperature, which also determines a critical pore width below which the interface localized-delocalized transition does not occur. If the walls exhibit critical wetting, the transition is shifted below Tw and for a model with the binding potential W(l)=A(T)l⁻²+B(T)l⁻³+..., where l is the location of the liquid-gas interface, the transition can be characterized by a dimensionless parameter κ=B/(AL), so that the fluid configuration with delocalized interface is stable in the interval between κ=-2/3 and κ ~ -0.23. Ми вивчаємо фазову поведiнку модельного плину, обмеженого двома рiзними паралельними стiнками у присутностi далекосяжних (дисперсiйних) сил. Передбачення, отриманi на основi макроскопiчних (геометричних) i мезоскопiчних аргументiв, порiвнюються з числовими розв’язками теорiї функцiоналу нелокальної густини. Розглянуто двi капiлярнi моделi. У випадку капiлярної моделi, що має двi (по-рiзному) адсорбуючi поверхнi, простi геометричнi аргументи приводять до узагальненого рiвняння Кельвiна, яке дуже точно локалiзує капiлярну конденсацiю, за умови, якщо обидвi стiнки лише частково змочуються. Якщо принаймнi одна зi стiнок знаходиться у режимi повного змочування, рiвняння Кельвiна слiд видозмiнити за рахунок ефекту товщини змочуючих плiвок, включивши поправку Дєрягiна. У другiй моделi розглянуто капiляр, утворений з двох конкуруючих стiнок: одна з них схильна до змочування, а друга — не змочується. У цьому випадку на границi роздiлу вiдбувається локалiзований-делокалiзований перехiд при двофазному спiвiснуваннi в об’ємi i при температурi T ∗(L), яка залежить вiд ширини пори L. Аналiз, виконаний за допомогою теорiї середнього поля, показує, що для стiнок, якi проявляють перехiд змочування першого роду при температурi Tw, Ts > T ∗(L) > Tw, де температура спiнодалi Ts може бути зв’язана з критичною температурою попереднього змочування, яка також визначає критичну ширину пори, нижче якої локалiзований-делокалiзований перехiд на границi роздiлу не вiдбувається. Якщо ж стiнки проявляють критичне змочування, тодi перехiд змiщується нижче за Tw, а для моделi з потенцiалом W (`) = A(T )` ⁻² + B(T )` ⁻³ + ···, де ` — мiсцезнаходження границi роздiлу мiж рiдиною i газом, перехiд можна характеризувати за допомогою безрозмiрного параметра κ = B/(AL), в результатi чого конфiгурацiя плину з делокалiзованою границею роздiлу є стабiльною в iнтервалi мiж κ = −2/3 i κ ≈ −0.23. 2016 Article Phase transitions of fluids in heterogeneous pores / A. Malijevský // Condensed Matter Physics. — 2016. — Т. 19, № 1. — С. 13604: 1–18. — Бібліогр.: 27 назв. — англ. 1607-324X PACS: 68.08.Bc, 05.70.Np, 05.70.Fh DOI:10.5488/CMP.19.13604 arXiv:1512.08957 http://dspace.nbuv.gov.ua/handle/123456789/155796 en Condensed Matter Physics Інститут фізики конденсованих систем НАН України |