Evaporation-Induced Branched Structures from Sessile Nanofluid Droplets

We investigate the formation of branched nanoparticle aggregates resulting from the evaporation of sessile nanofluid droplets of the copper water-based nanofluids experimentally. Both symmetric and asymmetric drying patterns were found as the sessile droplet evaporated. A kinetic Monte Carlo (KMC) approach is developed to explain the drying process in a circular domain, representing the top view of a drying sessile droplet. It is found that the lattice-gas-based Monte Carlo model can describe the nanoparticle self-assembly into a solid highly branched aggregate. While the chemical potential function is coupled to the nondimensional spherical droplet size during evaporation, the results reveal that the fingering contact line instabilities can emerge under a given condition and force the formation of a branched nanoparticle structure. The pattern comparison shows that the simulation results have a qualitative agreement with the experiments. The parameter study shows that the model parameters, such as domain diameter, chemical potential distribution, particle interaction energy, and so on, have significant influence on the resulting patterns

Evaporation-Induced Branched Structures from Sessile Nanofluid Droplets

We investigate the formation of branched nanoparticle aggregates resulting from the evaporation of sessile nanofluid droplets of the copper water-based nanofluids experimentally. Both symmetric and asymmetric drying patterns were found as the sessile droplet evaporated. A kinetic Monte Carlo (KMC) approach is developed to explain the drying process in a circular domain, representing the top view of a drying sessile droplet. It is found that the lattice-gas-based Monte Carlo model can describe the nanoparticle self-assembly into a solid highly branched aggregate. While the chemical potential function is coupled to the nondimensional spherical droplet size during evaporation, the results reveal that the fingering contact line instabilities can emerge under a given condition and force the formation of a branched nanoparticle structure. The pattern comparison shows that the simulation results have a qualitative agreement with the experiments. The parameter study shows that the model parameters, such as domain diameter, chemical potential distribution, particle interaction energy, and so on, have significant influence on the resulting patterns

Evaporation-Induced Branched Structures from Sessile Nanofluid Droplets

We investigate the formation of branched nanoparticle aggregates resulting from the evaporation of sessile nanofluid droplets of the copper water-based nanofluids experimentally. Both symmetric and asymmetric drying patterns were found as the sessile droplet evaporated. A kinetic Monte Carlo (KMC) approach is developed to explain the drying process in a circular domain, representing the top view of a drying sessile droplet. It is found that the lattice-gas-based Monte Carlo model can describe the nanoparticle self-assembly into a solid highly branched aggregate. While the chemical potential function is coupled to the nondimensional spherical droplet size during evaporation, the results reveal that the fingering contact line instabilities can emerge under a given condition and force the formation of a branched nanoparticle structure. The pattern comparison shows that the simulation results have a qualitative agreement with the experiments. The parameter study shows that the model parameters, such as domain diameter, chemical potential distribution, particle interaction energy, and so on, have significant influence on the resulting patterns

Elimination of the Coffee-Ring Effect by Promoting Particle Adsorption and Long-Range Interaction

A Monte Carlo model has been developed to investigate the transition from the coffee-ring deposition to the uniform coverage in drying pinned sessile colloidal droplets. The model applies the diffusion-limited aggregation (DLA) approach coupled with the biased random walk (BRW) to simulate the particle migration and agglomeration during the droplet drying process. It is shown that the simultaneous presence of the particle adsorption, long-range attraction, and circulatory motion processes is important for the transition from the coffee-ring effect to the uniform deposition of finally dried particles. The absence of one of the specified factors favors the coffee-ring deposition near the droplet boundary. The strong outward capillary flow on the latest evaporation stage can easily destroy the entire particle pre-ordering at the early drying stages. The formation of a robust particle structure is required to resist the outward flow and alter the coffee-ring effect

Evaporation-Induced Branched Structures from Sessile Nanofluid Droplets

We investigate the formation of branched nanoparticle aggregates resulting from the evaporation of sessile nanofluid droplets of the copper water-based nanofluids experimentally. Both symmetric and asymmetric drying patterns were found as the sessile droplet evaporated. A kinetic Monte Carlo (KMC) approach is developed to explain the drying process in a circular domain, representing the top view of a drying sessile droplet. It is found that the lattice-gas-based Monte Carlo model can describe the nanoparticle self-assembly into a solid highly branched aggregate. While the chemical potential function is coupled to the nondimensional spherical droplet size during evaporation, the results reveal that the fingering contact line instabilities can emerge under a given condition and force the formation of a branched nanoparticle structure. The pattern comparison shows that the simulation results have a qualitative agreement with the experiments. The parameter study shows that the model parameters, such as domain diameter, chemical potential distribution, particle interaction energy, and so on, have significant influence on the resulting patterns

Elimination of the Coffee-Ring Effect by Promoting Particle Adsorption and Long-Range Interaction

A Monte Carlo model has been developed to investigate the transition from the coffee-ring deposition to the uniform coverage in drying pinned sessile colloidal droplets. The model applies the diffusion-limited aggregation (DLA) approach coupled with the biased random walk (BRW) to simulate the particle migration and agglomeration during the droplet drying process. It is shown that the simultaneous presence of the particle adsorption, long-range attraction, and circulatory motion processes is important for the transition from the coffee-ring effect to the uniform deposition of finally dried particles. The absence of one of the specified factors favors the coffee-ring deposition near the droplet boundary. The strong outward capillary flow on the latest evaporation stage can easily destroy the entire particle pre-ordering at the early drying stages. The formation of a robust particle structure is required to resist the outward flow and alter the coffee-ring effect

Elimination of the Coffee-Ring Effect by Promoting Particle Adsorption and Long-Range Interaction

A Monte Carlo model has been developed to investigate the transition from the coffee-ring deposition to the uniform coverage in drying pinned sessile colloidal droplets. The model applies the diffusion-limited aggregation (DLA) approach coupled with the biased random walk (BRW) to simulate the particle migration and agglomeration during the droplet drying process. It is shown that the simultaneous presence of the particle adsorption, long-range attraction, and circulatory motion processes is important for the transition from the coffee-ring effect to the uniform deposition of finally dried particles. The absence of one of the specified factors favors the coffee-ring deposition near the droplet boundary. The strong outward capillary flow on the latest evaporation stage can easily destroy the entire particle pre-ordering at the early drying stages. The formation of a robust particle structure is required to resist the outward flow and alter the coffee-ring effect

Elimination of the Coffee-Ring Effect by Promoting Particle Adsorption and Long-Range Interaction

A Monte Carlo model has been developed to investigate the transition from the coffee-ring deposition to the uniform coverage in drying pinned sessile colloidal droplets. The model applies the diffusion-limited aggregation (DLA) approach coupled with the biased random walk (BRW) to simulate the particle migration and agglomeration during the droplet drying process. It is shown that the simultaneous presence of the particle adsorption, long-range attraction, and circulatory motion processes is important for the transition from the coffee-ring effect to the uniform deposition of finally dried particles. The absence of one of the specified factors favors the coffee-ring deposition near the droplet boundary. The strong outward capillary flow on the latest evaporation stage can easily destroy the entire particle pre-ordering at the early drying stages. The formation of a robust particle structure is required to resist the outward flow and alter the coffee-ring effect