freefoam-buoyantBoussinesqSimple: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/freefoam-buoyantBoussinesqSimple - from package: freefoam

You may install the required package with command apt-get install {package}
Error in other languages:
freefoam-buoyantBoussinesqSimple: bevel nie gevind nie
freefoam-buoyantBoussinesqSimple: comandă negăsită
freefoam-buoyantBoussinesqSimple: comando não encontrado
freefoam-buoyantBoussinesqSimple: commande introuvable
freefoam-buoyantBoussinesqSimple: command not found
freefoam-buoyantBoussinesqSimple: käsku ei ole
freefoam-buoyantBoussinesqSimple: không tìm thấy lệnh
freefoam-buoyantBoussinesqSimple: komanda nerasta
freefoam-buoyantBoussinesqSimple: Kommando nicht gefunden.
freefoam-buoyantBoussinesqSimple: kommandot finns inte
freefoam-buoyantBoussinesqSimple: komut yok
freefoam-buoyantBoussinesqSimple: nie znaleziono polecenia
freefoam-buoyantBoussinesqSimple: níor aimsíodh an t-ordú
freefoam-buoyantBoussinesqSimple: no se encontró la orden
freefoam-buoyantBoussinesqSimple: no s'ha trobat l'ordre
freefoam-buoyantBoussinesqSimple: opdracht niet gevonden
freefoam-buoyantBoussinesqSimple: parancs nem található
freefoam-buoyantBoussinesqSimple: perintah tidak ditemukan
freefoam-buoyantBoussinesqSimple: príkaz nenájdený
freefoam-buoyantBoussinesqSimple: příkaz nenalezen
freefoam-buoyantBoussinesqSimple: команда не найдена
freefoam-buoyantBoussinesqSimple: командата не е открита
freefoam-buoyantBoussinesqSimple: 命令找不到
freefoam-buoyantBoussinesqSimple: コマンドが見つかりません