Spatially vary velocity (#2491)

* initial add of GetVelocity and VelocityProperties

* bug fixes and first test implementation

* add documentation to parameters.rst

* Add error if |beta|>=1

* Check for |beta|>=1 in Juttner as well

* update comment on initial_distribution python script

* Doxygenization and floats in python

Co-authored-by: Axel Huebl <axel.huebl@plasma.ninja>

* Address comments in review

- Add units to analysis_distribution.py constants
- Move a comment on VelocityProperties constructor from implementation to header file

Co-authored-by: Hannah Klion <hannah.klion@gmail.com>
Co-authored-by: Axel Huebl <axel.huebl@plasma.ninja>

1 files changed, 71 insertions, 0 deletions

diff --git a/Source/Initialization/VelocityProperties.cpp b/Source/Initialization/VelocityProperties.cpp
new file mode 100644
index 000000000..6a0e74ecf
--- /dev/null
+++ b/Source/Initialization/VelocityProperties.cpp
@@ -0,0 +1,71 @@
+/* Copyright 2021 Hannah Klion
+ *
+ *
+ * This file is part of WarpX.
+ *
+ * License: BSD-3-Clause-LBNL
+ */
+
+#include "VelocityProperties.H"
+
+VelocityProperties::VelocityProperties (amrex::ParmParse& pp) {
+    // Set defaults
+    std::string vel_dist_s = "constant";
+    std::string vel_dir_s = "x";
+    m_velocity = 0;
+
+    pp.query("bulk_vel_dir", vel_dir_s);
+    if(vel_dir_s[0] == '-'){
+        m_sign_dir = -1;
+    }
+    else {
+        m_sign_dir = 1;
+    }
+
+    if ((vel_dir_s == "x" || vel_dir_s[1] == 'x') ||
+       (vel_dir_s == "X" || vel_dir_s[1] == 'X')){
+        m_dir = 0;
+    }
+    else if ((vel_dir_s == "y" || vel_dir_s[1] == 'y') ||
+               (vel_dir_s == "Y" || vel_dir_s[1] == 'Y')){
+        m_dir = 1;
+    }
+    else if ((vel_dir_s == "z" || vel_dir_s[1] == 'z') ||
+            (vel_dir_s == "Z" || vel_dir_s[1] == 'Z')) {
+        m_dir = 2;
+    }
+    else {
+        std::stringstream stringstream;
+        stringstream << "Cannot interpret <s_name>.bulk_vel_dir input '" << vel_dir_s <<
+            "'. Please enter +/- x, y, or z with no whitespace between the sign and" <<
+            " other character.";
+        vel_dir_s = stringstream.str();
+        amrex::Abort(vel_dir_s.c_str());
+    }
+
+    pp.query("beta_distribution_type", vel_dist_s);
+    if (vel_dist_s == "constant") {
+        queryWithParser(pp, "beta", m_velocity);
+        m_type = VelConstantValue;
+        if (m_velocity >= 1 || m_velocity <= -1) {
+            std::stringstream stringstream;
+            stringstream << "Magnitude of velocity beta = " << m_velocity <<
+                " is greater than or equal to 1";
+            amrex::Abort(stringstream.str().c_str());
+        }
+    }
+    else if (vel_dist_s == "parser") {
+        std::string str_beta_function;
+        Store_parserString(pp, "beta_function(x,y,z)", str_beta_function);
+        m_ptr_velocity_parser =
+            std::make_unique<amrex::Parser>(makeParser(str_beta_function,{"x","y","z"}));
+        m_type = VelParserFunction;
+    }
+    else {
+        std::stringstream stringstream;
+        std::string string;
+        stringstream << "Velocity distribution type '" << vel_dist_s << "' not recognized." << std::endl;
+        string = stringstream.str();
+        amrex::Abort(string.c_str());
+    }
+}