From 38d0e26200f919176307f72095ae6e6b63bc81e8 Mon Sep 17 00:00:00 2001 From: William Fullmer Date: Fri, 26 Mar 2021 16:24:19 -0400 Subject: [PATCH] add note on transient BCs --- .../source/inputs/InputsProblemDefinition.rst | 26 +++++++++++++++++++ 1 file changed, 26 insertions(+) diff --git a/docs/source/inputs/InputsProblemDefinition.rst b/docs/source/inputs/InputsProblemDefinition.rst index 9a1a978..5acae56 100644 --- a/docs/source/inputs/InputsProblemDefinition.rst +++ b/docs/source/inputs/InputsProblemDefinition.rst @@ -649,6 +649,32 @@ Below is an example for specifying boundary conditions for a fluid `myfluid`. bc.outflow.myfluid.pressure = 0.0 +Transient Boundary Conditions +----------------------------- + +Velocity, temperature, and pressure boundary conditions may also be specified as a +function of time simply by adding a new column. The time value is entered in the +new first column. We can make the `mi` boundary condition above time-dependent +by replacing: + +.. code-block:: none + + bc.inflow.myfluid.velocity = 0.0 0.0 0.0 0.0 + bc.inflow.myfluid.velocity = 3.0 0.015 0.0 0.0 + bc.inflow.myfluid.temperature = 0.0 300 + bc.inflow.myfluid.temperature = 2.99 300 + bc.inflow.myfluid.temperature = 3.0 500 + bc.inflow.myfluid.temperature = 4.0 500 + bc.inflow.myfluid.temperature = 4.01 300 + +In the above example, the inflow velocity is accelerated from zero to its +final value over a period of three seconds. Linear interpolation is used in +between discrete time values and held constant at the last time value. The +temperature sees an abrupt spike from 300 up to 500 at t = 3s and then back +down again after 4s. Note that the timestep is not adjusted to sync with +transient BCs. + + Boundary Conditions on Embedded Boundaries ------------------------------------------ -- GitLab