Hi,

Recently I noticed the using implicit time stepping can boost simulation a lot. I checked several post about this in the forum. I tried recommended setups by Niki but it seems my solver kept blowing up after a while. My flow configuration is that I am running a 3D flow around an aerofoil with compressible solver. I restarted my simulation with sdirk43 with rk45 pseudo scheme. I have used standard rk45 scheme for the same case which works well even for slightly larger dt. I pasted my configuration file down. Can you recognise what could possibly the problem? And what is the best way to tune those parameters since there’re a lot. Thanks in ahead.

Best wishes,

Zhenyang

```
[solver]
system = navier-stokes
order = 2
anti-alias = flux
viscosity-correction = sutherland
;[solver-time-integrator]
;formulation = std
;scheme = rk45
;controller = pi
;tstart = 0.0
;tend = 5000.001
;dt = 0.03
;atol = 0.000001
;rtol = 0.000001
;errest-norm = l2
;safety-fact = 0.9
;min-fact = 0.15 ; 0.1 - 0.5
;max-fact = 6 ; 2.0 - 6.0
[solver-time-integrator]
formulation = dual
scheme = sdirk43
pseudo-scheme = rk45
tstart = 0.0
tend = 5000.001
dt = 0.02
controller = none
pseudo-dt = 0.0005
pseudo-niters-max = 100
pseudo-resid-tol = 1e-6
pseudo-resid-norm = uniform ; l2
pseudo-controller = local-pi ; only works for rk34 and rk45
atol = 0.000001
safety-fact = 0.9
min-fact = 0.1 ; 0.1 - 0.5
max-fact = 6 ; 2.0 - 6.0
pseudo-dt-max-mult = 3 ; 2 - 5
[solver-dual-time-integrator-multip]
pseudo-dt-fact = 2.3
cycle = [(2, 1), (1, 1), (0, 3), (1, 1), (2, 5)]
[solver-interfaces]
riemann-solver = hllc
ldg-beta = 0.5
ldg-tau = 0.1
[solver-elements-hex]
soln-pts = gauss-legendre
quad-deg = 7
quad-pts = gauss-legendre
[solver-elements-hex-mg-p2]
soln-pts = gauss-legendre
quad-deg = 7
quad-pts = gauss-legendre
[solver-elements-hex-mg-p1]
soln-pts = gauss-legendre
quad-deg = 5
quad-pts = gauss-legendre
[solver-elements-hex-mg-p0]
soln-pts = gauss-legendre
quad-deg = 3
quad-pts = gauss-legendre
... more element types
```