Simple specie diffusion problem with Fundamental solution of Laplace Equation
 

Hello Everybody
First of all, dear members, I would like to thank you for spending your precious time in reading my problem and giving usual suggestions hopefully.
I am simulating a very fundamental droplet evaporation problem to solve the steady state Laplace equation to calculate the concentration field around the droplet.
The boundary conditions are fundamental dirichlet and Neumann boundary conditions at four walls as shown in the figure. I have used the 1 mm axis symmetric hemisphere droplet and the far field conditions are achieved at 200 times of the Radius. I have achieved the grid independent and used already very fine grid near the droplet at nearly 1um or even below that. So far field boundary and grid resolution is not the problem.
I have used both the FVM solver ANSYS Fluent and FEM solver MATLAB PDE tool box. However, both give me incorrect results at the same extent.
The problem is that the concertation field calculated by both Fluent and matlab is not according the already published data. I have attached the comparison results between the results from the paper (International Journal of Thermal Sciences 84 (2014) 300e308). For your reference you can look at the concentration iso line at 4mm location in three of the figures. Similarly, the concentration gradient on the surface of the droplet is also not same to this paper.
Therefore, I kindly request you what is the possible answer to this numerical dilemma being a very simple problem of solving the Laplace equation. I am extremely thankful from the core of my heart for your kind suggestions explanation.
Note: I am just repeating this paper so every condition is same. Also I cross checked this paper results to be correct with other literature.
Regards,
Khan