Dear Colleague,

A number of bugs have been found in the Lattice Boltzmann Equation (LBE) code of 
DL_MESO 2.6 and one of its utilities.

Calculations of density and concentration gradients for the Swift free-energy 
interaction model were discovered to be carried out incorrectly due to incorrect 
specification of neighbouring grid points and an incorrect value for one of the 
weighting factors used in the stencil. Errors were also discovered in the 
expressions used to calculate the Galilean invariance coefficients used for the 
same interaction model. (Many thanks are due to Khaled Al-Ghaithi at the 
University of Leeds for bringing these bugs to our attention.)

When using the Redlich-Kwong and Carnahan-Starling-Redlich-Kwong equations of 
state with either Shan-Chen or Swift interactions and a constant system 
temperature, the coefficient for molecular attraction is incorrectly scaled 
after being read from the lbin.sys input file.

A bug has also been discovered when using Multiple Relaxation Time (MRT) 
collisions: the bulk relaxation time for each fluid is erroneously replaced with 
the value for antisymmetric relaxation time for the Two Relaxation Time (TRT) 
collision scheme due to an error in a logic condition.

The lbeinitcreate.cpp pre-processing utility for creating lbin.init input files 
incorrectly sets the density for continuous fluids to non-zero values when a 
drop of a different fluid is inserted.

As all of the above bugs require changing several lines of code, we therefore 
strongly recommend that all registered users of DL_MESO version 2.6 should re-
download the code using the instructions they received on registration to obtain 
the correct version of the software. The decryption password has not changed and 
thus re-registration is not required.

Michael Seaton
2017-04-14