Validation of the poke-flow technique combined with simulations of fluid flow for determining viscosities in samples with small volumes and high viscosities

Abstract

Abstract. Viscosity in particles consisting of secondary organic material (SOM) has recently become an area of research focus, since information on viscosity is needed to predict the environmental impacts of SOM particles. Recently Renbaum-Wolff et al. (2013a) developed a poke-flow technique that was combined with simulations of fluid flow to constrain the viscosities of SOM samples of 1-5 mg mass, roughly the maximum that may be collected from environmental chambers or flow tubes on a reasonable timescale. The current manuscript expands on the initial validation experiments carried out by Renbaum-Wolff et al. First, the poke-flow technique combined with simulations of fluid flow was used to determine the viscosity of sucrose-water particles over a relatively wide range of relative humidities (RHs). The lower and upper limits of viscosity at 59 % RH were 1.0 × 10 1 and 1.6 × 10 4 Pa s, whilst at 37 % RH the corresponding values were 7.2 × 10 4 and 4.7 × 10 6 Pa s, respectively. The results are in good agreement with recent measurements by Quintas et al. (2006) and Power et al. (2013). Second, the approach was used to determine the viscosity of two polybutene standards. The simulated lower and upper limits of viscosity for standard #1 was 2.0 × 10 2 and 1.2 × 10 4 Pa s, whilst for standard #2 the corresponding values were 3.1 × 10 2 and 2.4 × 10 4 Pa s. These values are in good agreement with values reported by the manufacturer. The results for both the sucrose-water particles and the polybutene standards show that the poke-flow technique combined with simulations of fluid flow is capable of providing both lower and upper limits of viscosity that are consistent with literature or measured values when the viscosity of the particles are in the range of ≈ 5 × 10 2 to ≈ 3 × 10 6 Pa s.

Relative humidity-dependent viscosity of secondary organic material from toluene photo-oxidation and possible implications for organic particulate matter over megacities

“…The qualitative method of poking an inorganic particle to determine its phase (i.e., solid or liquid) was introduced by Murray et al (2012). Renbaum-Wolff et al (2013a) and Grayson et al (2015) expanded on this method by measuring the characteristic flow time of a material after poking and extracting viscosity information from simulations of fluid flow. Briefly, supermicron toluene-derived SOM particles deposited on a hydrophobic substrate (toluene 5-8, Table 1) were placed inside a flow cell with RH control.…”

“…To determine viscosities from τ exp, flow , simulations of fluid flow were carried out with the finite-element analysis software package, COMSOL Multiphysics (Renbaum-Wolff et al, 2013a; Grayson et al, 2015). The mesh size used in the simulations was 4.04-90.9 nm.…”

“…Most qualitative and quantitative measurements of viscosity and diffusion rates within organic particulate matter have focused on SOM generated from biogenic VOCs such as α-pinene and isoprene (Virtanen et al, 2010;Cappa and Wilson, 2011;Perraud et al, 2012;Saukko et al, 2012;Abramson et al, 2013;Robinson et al, 2013;RenbaumWolff et al, 2013a;Bateman et al, 2015;Kidd et al, 2014;Pajunoja et al, 2014;Wang et al, 2015;Grayson et al, 2015;Song et al, 2015). Recently, the viscosity and diffusion rates within SOM particles generated from anthropogenic VOCs have also been investigated.…”

Dynamic viscosity mapping of the oxidation of squalene aerosol particles

“…An aerosol's viscous state also has direct implications on the particle morphology, phase behaviour, optical properties, aging processes and lifetime. At the same time, only few direct measurement methods are available for monitoring such properties 1, [6][7][8][9][10][11][12][13][14][15][16] . Recently, we have demonstrated that viscosity of model organic aerosols, such as oleic acid droplets, and secondary organic aerosols (SOA) produced from the oxidation of myrcene or -pinene can be measured and imaged in a spatially and time-resolved manner using Fluorescence Lifetime Imaging Microscopy (FLIM) of molecular rotors 17 .…”

Review of Viscosities and Phases of Biogenic Secondary Organic Aerosols

“…Marcolli et al, 2004). 그리고 대부분의 에어로졸 성장 모델에서 에어로졸은 점성도가 낮다고 가정되어 왔다 (Hallquist et al, 2009 Bateman et al, 2015;Li et al, 2015), (2) beadmobility와 poke-flow 방법 Hinks et al, 2016;Song et al, 2016;Grayson et al, 2015;Song et al, 2015;Renbaum-Wolff et al, 2013a, b Loza et al, 2013;Perraud et al, 2012), (2) bounce 특성 이용 (Kidd et al, 2014;Saukko et al, 2012;Virtanen et al, 2010Virtanen et al, , 2011, (3) 이차유기에어로 졸의 증발률 (evaporation rate) 이용 (Cappa and Wilson, 2011;Vaden et al, 2011), (4) 이차유기에어로졸의 반응 성 (reactivity) 측정 Kuwata and Martin, 2012 n/a, n/a, n/a n/a, n/a, n/a Particle rebound Pajunoja et al (2015) α-pinene . Optical images of a SOA particle produced from isoprene photo-oxidation at 80% relative humidity at 295 K which were recorded for a bead-mobility experiment.…”