Using variable with fix ave/spatial

Submitted by vinaym on Mon, 09/25/2017 - 16:07

Hello,

I want to determine average of velocity square < (Vx^2) > and later average it in a band at different heights in the domain.
I tried to do so in the following way using variable and fix ave/spatial command.

variable gvx equal vx*vx
variable gvy equal vy*vy
variable gvz equal vz*vz
fix gvel all ave/spatial 1 1000 1000 z lower 0.01 v_gvx v_gvy v_gvz file meanv.txt

However, I get an error ERROR: Fix ave/spatial variable is not atom-style variable (../fix_ave_spatial.cpp:365)

What am I missing here?

Thanks and kind regards,
Vinay