Research Data

Dataset containing phase-averaged 2-D velocity vector fields of the re-entrant jet in a cavitating axisymmetric venturi underlying the publication: Gawandalkar U.U., Poelma C., The structure of near-wall re-entrant flow and its influence on cloud cavitation instability. Experiments in Fluids (2022). doi.org/10.1007/s00348-022-03417-6

Authors: U.U. Gawandalkar (u.u.gawandalkar@tudelft.nl)
         C. Poelma        (c.poelma@tudelft.nl)

Delft University of Technology
Multiphase Systems, Mechanical Engineering
Mekelweg 2, 
2628 CD Delft, The Netherlands

The data in this file contains the phase-averaged velocity vector fields in x-z plane of the re-entrant jet below a vapour cavity in a part of a shedding cycle (t/T = 0.30-0.58). T is the shedding time period. The colorbar shows the axial velocity (u_x) of the re-entrant jet, where bulk flow direction is from left to right and re-entrant jet flow direction to right to left.
This data is obtained with a time-resolved tomographic particle image velocimetry (tomo-PIV) at the Laboratory for Aero and Hydrodynamics in Delft. The purpose of this study was to visualise and quantify the complex near-wall liquid film below the vapour cavity as the cavity grows and detaches to decipher its exact role in cavity detachment leading to cloud cavitation at:
throat velocity   (U_t [ms^-1])  =  10.4    
cavitation number (sigma [-])    =  0.97     

Full details of the study can be found in: Gawandalkar U.U., Poelma C., The structure of near-wall re-entrant flow and its influence on cloud cavitation instability. Experiments in Fluids (2022). doi.org/10.1007/s00348-022-03417-6

Data description:
The phase-averaged velocity vector data are included at six different time instances in a cycle as MATLAb compatible .mat files, i.e. t/T = 0.3, 0.38, 0.13, 0.48, 0.53, 0.58, wherein at each phase-instance (t/T), velocity field has been averaged over 40 shedding cycles using the approach detailed in our paper. 
The overview of datafiles is provided here:

Filename	        t/T   
-------------------------------
vel_t_0_30.mat    	0.30	    
vel_t_0_38.mat    	0.38	
vel_t_0_43.mat    	0.43  
vel_t_0_48.mat          0.48
vel_t_0_53.mat    	0.53
vel_t_0_58.mat  	0.58	   

Each .mat file contains 4 columns. First column contains x-coordinate, second column contains z-coordinate, third column contains phase-averaged axial velocity (u_x) and fourth column contains phase-averaged z velocity. The x and z spatial-coordinates are in mm, while velocities are in [ms^-1]

A sample code for quick visualisation of velocity vector field using Matlab is given below:
--------------------------------------------------------------------------------------------------------------------------
load('vel_t_0_30.mat');
oo=figure; 
set(gcf,'Position',[50 100 1500 150]);
quiver(Vel(:, 1) ,Vel(:, 2), Vel(:, 3), Vel(:, 4), 1, 'filled', 'k');
set(gca,'fontsize',14 , 'FontName', 'Times');
xlabel('$x$ $[mm]$', 'fontsize', 16, 'interpreter', 'latex'); 
ylabel('$z$ $[mm]$', 'fontsize', 16, 'interpreter', 'latex');
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A movie showing temporal evolution of re-entrant liquid flow as the cavity grows at σ = 0.97 is also included as 'S1.avi'.

Licensing/usage:
Other researchers may use this data in their own work (CC BY 4.0). The dataset is available at the 4TU.Centre for Research Data via, doi.org/10.4121/41ee4f1e-17ae-4e8f-9941-260d7881d04b.

Funding:
This work is funded by ERC Consolidator Grant 725183 ‘OpaqueFlows’. 


